If I actually had the choice of being able to go down to the shops and by a PC game at a reasonable price, I'd probably feel more inclined to want to buy all my PC games via retail to have the boxes, manual and media.
But seeing as digital distribution is the only reasonable way I can by most games, I was initially forced into using it. Now, having used it for a good 5 years or so, it's now no different than retail purchasing for me. I feel I own the game in either way, and have just as much ability to play them (if not slightly more so via DD -- no need for the media/no DVD cracks).
Looking at boxes on a shelf, vs images on a site, or names on a client, makes no difference to me now. A game is a game. It must be installed in its digital form in order to be played and it is while I play them that I truly feel like I own them.

Haven't used it, but i read this article a while back about some software to organise your collections (real or virtual).
http://lifehacker.com/5335745/mycollections-organizes-your-media-apps-and-more
(windows only)
Like bansama i was forced into DD (and probably for the same reason), but on the whole i like it.
I do agree that having too many accounts/softwares is annoying. To be honest, I never actually buy anything from gamersgate or impulse... i always look at their offers, and i'm tempted, but i have everything on steam... so i end up just waiting for a steam sale.. and i end up paying more for the steam version because it's more convenient.
I know what you mean about virtual goods feeling they have less value... but there does seem to be a difference between goods you BUY&download and just goods you download. the fact i've paid money for it makes it feel more real.
I used to love collecting video games back when they came in the big boxes with manuals, but they lost a lot of the magic when they started coming in DVD cases... so the jump to digital wasn't so painful.
I still have a few of my alltime faves in boxes (SS2, i76, Tie Fighter, etc..) but i was forced to throw out a lot of the boxes to save space anyway.
So, in summary... everything on steam would work for me. ;-)

I like having big shiny boxes and did NOT like the move to DVD cases, still I like having a copy on CD/DVD-ROM as it feels safer than storing it on HDD, and anyone can see how much of a geek I am by simply looking at my shelves (where I have a crapload of games, but would have more had all my games from GOG been in physical form as well).
Go battle.net? Though it's only a single publisher/developer (Blizzard), it IS a good system.
All their (current*) games can be bought both online and retail, online-bought games are automatically added to a virtual shelf, not entirely unlike the GOG one, and physical copies can be added by simply entering the serial key. Games on the shelf can be downloaded as much as you'd like, and I don't even think there's any other DRM than the serial key you need to enter at install time (also accessible from your battle.net account), so you could even help your pre-broadband friend as he could use the copy you downloaded with his key and both would still have a perfectly legal copy of the game.
Also, the downloader for each game (and updates, at least for World of Warcraft) is simply a customised bittorrent client, albeit with the .torrent file built-in (that can be extracted from the Windows client by dodgy 3rd-party tools - no tools needed in Mac land), so there's no proprietary client, or strange installation (as steam does) going on.
*current games, because Warcraft 1 and 2, and Diablo 1 are not available (yet) though some retail stores still sell cheap copies of them (of course, only Warcraft 2 battle.net edition has a serial key, neither the two 1's nor the original WC2 or its expansion do), and I don't know wether they'll remove Diablo 2 and Starcraft when their sequels are released - I hope they'll not remove them from downloading though, just buying if at all.
Oh, and to add on to the poster above linking to a piece of Windows software for neatly cataloguing your stuff, here are two for the Mac (especially the first one have gotten good reviews, and the second exist for Windows as well but doesn't seem do have the nice virtual shelves the first one does):
Delicious Library
Librarian Pro

Since reading here some of the issues some people have had with Steam and the potential that, yes, if they go down or if they close my account or if it gets hacked, then yes, i lose everything I've purchased, I've stopped buying from them on a whim (which I've done when the offers are good). Buying from GOG gives me full ownership and even if the games are old, it doesn't mean they're less fun. I'm playing to entertain myself and I usually do it against the computer on my own, so who cares if I'm not playing the latest game?
I'll still Buy Starcraft 2 and Diablo 3 when they come out but those two are probably the only games I'll be spending more than twenty bucks on in quite some time.

Exactly. I've been avoiding D2D and Gamersgate for a while now because of this reason. I have games on Steam, Impulse and GOG, and God-knows-what-other-games-I-actually-own-but-have-forgotten. I personally don't like having to constantly keep track of what I've bought. Something about it just doesn't feel right, and I'm also worried I may lose the .txt file or whatever app I choose to keep track in.
One of the things that really annoys me about digital distribution is if the developer closes down, you may not be able to get it back anymore. I've bought this game called Zombie Smashers X2, and it was smashing good fun. However, the link to my download has now expired, and the developer has ceased all distribution on it, so I can't get my hands on it anymore. I don't feel ripped off in the sense that I don't get what I paid for, I just feel that I've lost part of the ownership of the game. It almost feels like a rental service at times.

No offense, but that is your own fault for not backing it up when you originally downloaded it. You can't blame digital distribution as a whole for your mistakes.

That's an extra bit of hassle that you don't get with a proper DVD/CD-based purchase.

Not really. Like I said, I simply download it to my external HDD and it is already backed up. No more hassle than ripping the plastic wrap off of a CD/DVD case.

I use MobyGames. The game descriptions are quite good and i usually just change the two pics on the details sections cause the ones i get from MobyGames are too small (when you click on them)
The custom user field tags are quite good to link the game descripton to video and audio playlists, and galleries with all the pics and ingame screenshots.

I feel the TS's issues are ones of consumption, not the medium itself.
GOG truly represents the pinacle of DD, EXCEPT the recent Flashpoint/Codemasters Racing fiascos. They have a REFUND policy, they actually grant OWNERSHIP of the titles you buy, and the prices are CHEAPER than retail in every practical manner.
The only aspect of the holy trinity GOG lacks is resalability. And I mean, with games costing $6 or $10, this is not a needed feature.
I have been a long time Steam member, I have 123 games now, but I have to say, I have almost exclusively switched over to GOG just because they are doing things damn right!

Huh? I thought all sales are final and non-refundable...

Yup, they are:
http://www.gog.com/en/support/policies/terms_of_use]
Refund Policy: All Sales are final. [/url]

I couldn't afford any backup media back then, when DVD/CD writers were still more expensive, so you're saying it's my fault for being a poor student?
I am not blaming digital distribution as a whole. On the contrary, this is why I'm thankful for the presence of Steam and Impulse - to offer a mirror for me to download my games anytime I want. It's the wildly varying, mass arrays of digital distribution that I'm not comfortable with.

Well, I don't have an external HDD.