I have been lucky enough to come across several great retail compilations of 'vintage' PC games over the years, including the following:
-DOOM Collector's Edition (Ultimate DOOM, DOOM II, Final DOOM)
-Interplay Anthology 10th Anniversary (Out of This World, Star Trek 25th Anniv, Tonetown, lots of early 90s and late 80s RPGs)
-Interplay Anthology 15th Anniversary (Lost Vikings 2:Norse by Norsewest, Descent, Redneck Rampage...)
-King's Quest Collection (the one with Laura Bow 1+2 and some other nice extras)
-Lost Adventures of Legend (Gateway 1+2, Timequest, Eric the Unready, Spellcasting trilogy, Companions of Xanth)
-LucasArts Archives Volume 1 (Indy Fate of Atlantis, Day of the Tentacle, Sam & Max Hit the Road)

Anyway, I'm hoping to hear what good retro PC compilations others have stumbled upon. Sadly, GOG can't republish all the classics. I mainly play adventure games, but I'm also really into classic FPS (solo run-and-gun) and I'm totally up for giving any genre a try. I know there are good new-er compilations like the Orange Box (which I have) and Star Wars Best of PC, but I'm mainly interested in older compilations. Any suggestions would be much appreciated. Thanks! :-)

I have the Origin Ultima Collection, Interplay's Ultimate Wizardry Archives, and the Limited Edition of MM6 sitting on my games shelf. The Limited Edition can now easily be obtained from this site for $10.

If you're not really picky, you can easily find SSI's gold, black and white box compilations on eBay for inexpensive prices. Of course you have to be lucky too, but on average I see them going at around $10 or so. They're less expensive than their singular counterparts because most people just want to buy these games for collection's sake. Limited Ed or Millenium Ed? They're two different things. The Millenium Ed's contents are more skimpy though they come with the first 6 MM games. The Limited Ed comes with a huge motherload of goodies, though it only has Mandate of Heaven.

Hmm, there's Fallout Trilogy (it has a less confusing title now, something like Fallout Collection or something) that has 1, 2, and Tactics on it. You'd save a little money with GoG though since it goes for $20 (too bad I wasn't a GoG member then). That collection is still in many retail stores.

Blizzard still sells their Diablo collection which is Diablo 1, 2, and the Diablo 2 expansion.

The Wing Commander: Kilrathi Saga is a good buy if you can find it, and have a computer that can run Win 95 games well. WC1 and 2 are graphically inferior, but the engines run at a stable speed, the sound is improved, and they include the expansions that EA is holding out on us.

C&C the First Decade used to be a great deal until EA started giving away most of the games on that collection for download.

LucasArts has most of their Star Wars games released in various collections. I just wish they would include some of their much earlier titles. Jedi Outcast is about as far back as they go.

Was the King's Quest thing actually the 'Roberta Williams Anthology' - I have that
I've got some '20 great games' thing which I didn't pay much attention to at the time as this was Win95 era and they were mainly DOS and a pain to get working but I've had a look recently and its got MoO, Star Control (the first one) Kyrandia 2: Hand of Hate and a bunch of other good stuff so I may have to get my gead around DOSBox soon...
'The Biggest names the Best Games 4' (an EA compilation) had System Shock 2, Dungeon Keeper 2 and others
A four pack of Lucas Arts Adventures - Frim Fandango, Full Throttle, The Dig and Sam and Max
I'm sure there were others - Master of MAgic was on 1 complation but a friend nicked the disk leaving me with just the German version!

Thanks, everybody! I'm happy to see so many replies -- I don't make many posts, or at least I haven't so far - so it's exciting for me. I may also be replying to people in a nonstandard way, so I apologize in advance for that...

@Fever_Discordia, I checked and what I have is the "King's Quest Collection Series" from 1997, released one year after the Roberta Williams Anthology -- it's basically the same thing game-wise, though it doesn't have Dark Crystal. That LucasArts pack sounds awesome, I haven't seen one with Grim Fandango like that, although I did pick it up a while back as a standalone game.

@tbirdo - It is a shame they're holding out on some of the older stuff. Jedi Outcast is awesome, though, I must say - it's one of my favorite FPS games. It was really like a slightly modernized Jedi Knight - pretty similar in gameplay.

@lowyhong - Sadly, I haven't much gotten into strategy or sim type games, although oddly enough my introduction to Legend's text hybrid adventures was through an SSI pack called "Galactic Challenge" which had three strategy games (Star Control I+II and Renegade), and Legend's "Frederik Pohl's Gateway" (my icon is from the title screen). Unfortunately, I never gave the other games the time of day back then - I was a young teenager at that point and I no longer have that pack. Maybe some day, although I'd like to find something pretty accessible to start with (I'm playing the free Wesnoth now - is that a decent starter strategy game?).

@DaveO-MM - I probably won't give any Ultima games a try for a while, but when I do, can you recommend a good 'beginner's' Ultima? I'm not afraid of pixels but I am afraid of really clunky interfaces...

The Ultimate Quake is my favorite compilation. All of the true Quakes (1, 2, &3) in a single jewel case.

http://www.mobygames.com/game/windows/ultimate-quake

I'm considering getting that if I can find a boxed version... was it ever released in a box? I know often publishers start off with boxes then move just to jewel cases. It would make a nice addition to my somewhat-modest box collection.

I recently finished Quake 1 which I got from Steam - I love it! The gameplay is a lot like the DOOM games but with much more clever enemy ambushes and even a few cool puzzles. I've owned Quake II since I was young but haven't played it much -- the pacing is much slower than Quake, if I recall, but it still seems like a lot of fun. (I was bad at actually playing my games for very long when I was a kid, but in recent years I've been a little better at beating them and not finding them as 'intimidating').

Oh I forgot to mention the Myst Trilogy. Not of much value if you don't like Myst, I mainly bought it for nostalgia and Riven, which I had never played. Strangly, Myst 3 doesn't seem to be on GoG yet.

Mine came in a cardboard box. One of the small ones that resembles a really fat DVD case (same dimensions as Doom3's box). It's was pretty no thrills packaging. I threw mine away.

Be aware that it doesn't include any expansion packs (they're nice but not essential for these games in my opinion). I like this compilation because Quake goes on all my machines and this is a very convenient form to add to a pc with a fresh OS install*.

*I haven't tried Win7 64 yet

It's probably worth mentioning that Quake 3 is basically free, but with ads, as Quake Live. Of course you can skip the ads and get maps early if you give ID money. I've never played Quake Live myself. I'm more into TF2 for my online shooter fix.

Quake Live is too locked down for me. You can't play any mods which is half the appeal of id games.

Thanks for the suggestion. :)

In regards to Might & Magic, it's definitely the Limited Edition which contains MM1 to MM6 and has a cloth map.

For the Ultima question, I'd start with Ultima 3 and work my way up.

I download abandonware and torrent stuff all the time. Funny thing is, I own legit copies of these games, sometimes more than one, and ironically am contributing to those "statistics" that DRM-worshipping corporate heads like to wave about during boardroom meetings.