I actually misread the title at first asking if people backed up their GOG games, not sure how I made that distinction since GOG and Steam aren't even similar looking. I actually do keep some of the installs on hang for GOG games cause it can be a pain to redownload the larger ones due to their download speed being a tad slow.

As for Steam? Never really thought of it, to be honest. I certainly hope Steam doesn't go anywhere anytime soon, cause I've got a number of games I've bought and haven't finished yet. Heh, now I'm gonna start feeling a bit paranoid about my Steam games. :p

Nah. I backup my GOG and Gamersgate purchases religiously and backup the cracks for my disc games but if any service will be around for quite a while it's Steam.

Try to check beforehand, as I have read somewhere that Steam offline mode works for around 2-3 months and than you have to online at least for a short while. Hopefully there would not be any unpleasant surprises.

Yeah, I do this all the time. I basically download the game, shut down Steam, then use Winrar to create a RAR archive split up into several 100 MB files (stored with no compression.) Once that's done, I uninstall and back up the game to DVD-R.

When I want to reinstall, I just start the download, then stop it, shut down Steam, extract the contents of the RAR to the steamapps folder, restart Steam, and let it download anything it might need.

I do this because of my third world internet and Steam's download servers being unreliable during certain periods. Plus this way I can help a pal of mine who has even worse internet than I do, I just let him have my backup files and he can download what he needs.

I do this too, except that I compress the files in a single 7-zip file and store it in my network HDD. I usually share those with my brother because there is no way we were gonna download 11GB of Portal 2 twice to play co-op.

I've started doing this recently but only with bigger games, simply because I have slow internet (it takes me about an hour to download 1GB at my fastest). As has been mentioned above, I install, then put the game folder from within steamapps into a RAR archive.

EDIT: Oh, and then I put the RAR archive on my external hard drive.

I've used the backup method for some of the larger games and it worked pretty well, though I think it only backs up the base game and no updates because when I went to reinstall Team Fortress 2 there was still a lot of content it had to download (over a hour download time, don't remember how much date though) and I doubt there were that many patches in the month between me backing it up and reinstalling it, though I could be wrong.
For game that I don't care about the multiplayer on I just pirate my backups.

I nearly always backup my DRM-Free games but on the other side I never use the Steam backup function, because of the DRM nature of Steam the backup are totally useless except to spare bandwidth re-downloading the game.

But I hardly have more than one or two Steam games installed at once on my "DRM-using games Windows" partition and I have a fast enough connection to be able to re-download any games in 1-3 hours max.

TF2 gets about 150 to 250 MB of patches every two weeks... sometimes more. All those hats take up a lot of space.

That's a lot. Well then, ignore that part of my post, seems those were new patches after all.

I've been using the built in backup since the fist games I got - one file per game on an external HDD. When I started my download speed was a lot lower so I wouldn't want to wait for a full download. Now, the download speed is up but the games are now so much bigger that it is still better than waiting to re-download. Not that I have ever had to.

Also I don't want all the games on my main HDD at once - most of them are "off-line".

This thread makes me feel really lazy...

Nope.

Whups! This just reminded me ... I forgot to backup Dear Esther

<Rushes off to make a backup>