jazz jackrabbit is the best platformer of all time, hands down, and jj2 is even better than the first

Hmmm how about Ares: Extinction Agenda?
May be something like Bit.Trip.Runner?
Sideway New York may be?
Of course, you could also just dig into the Sega Genesis platformers - I recall Steam has quite some on sale.

There is no where I can buy that though correct? I'm sure it's on freeware sites but I suck at working DOSBOX myself.
Oh yeah I played a demo of that and liked it. Then I got it in some Steam bundle and forgot it, thanks for reminding me! XD

well, JJ2 doesn't require dosbox. amazon has some new and used copies on the cheap.

edit: you can also look for JJ2 holiday hare. it's also on amazon and i think it has extra stuff

I can hardly believe that no one mentioned Monolith's Captain Claw, one of the best platformer on PC (http://www.mobygames.com/game/windows/claw). On the other hand, good luck finding it (hope it comes on GOG soon).

Lately I've been loving Explodemon

For a completely different kind of experience try Wik and the Fable of Souls

The first two Duke Nukem games are great classics, in my opinion.

You could also try the fan made

Keen 7
http://www.pckf.com/viewtopic.php?t=566

Keen 8
http://www.pckf.com/viewtopic.php?t=762

Keen 9
http://www.pckf.com/viewtopic.php?t=1808

I second the recommendations for Claw, Frogatto & Friends, Iji and Climb to the Top of the Castle.

As for older games, I think nobody mentioned Halloween Harry: Alien Carnage (1994) and Hocus Pocus (1994) yet? Or how about the The Hobbit (2003)?

I'm currently playing and enjoying Fortune Summoners: Secret of the Elemental Stone which is actually a sidescrolling 2D RPG not a real Platformer, but it draws heavily from Platformer elements, so you could watch a gameplay video and see if you might enjoy it nevertheless. (Or is it actually a sidescrolling 2D platformer with some cute 'cutscenes' in between and not really a RPG? Not sure. :D )

Just throw me a shout if you need help with dosbox. While I'm no Dosbox wizard, I can most likely help you get Jazz Jacrabbit to run. In fact, if you want to see how well it goes, give the Shareware version a try. Let dosbox set the cycles count for this one, it should work just fine. Here is how to get the game to run:
Unzip the file to whatever dir you want (though the shorter the path from the root dir on your HD it is, the easier). Give the folder a nice and easy name, such as Jazz.

Then just type in:
mount c "dir where your jazz folder is" (for an example: mount c d:\games)
c:\
cd jazz
Setup (pick soundblaster 16, and you do of course have a computer capable of handling ultra quality)
Then exit the stup and just type in Jazz
And now the game should run

Vessel - So cool I just had to make a thread about it :-P

I would recommend Iji and La-Mulana. The former is an linear stage-based experience, focusing on how you approach firefights. Feels like classic shooter-platformer games, like Jazz Jackrabbit. An freeware game.

La-Mulana is the lovechild of Indiana Jones (aesthetics), Alucard (platforming), and Zelda. (Puzzles) The PC-MSX version is freeware, and I highly recommend it.

Some of these are probably closer to action-adventures than "pure" platformers:

Tomb raider series
Prince of Persia series
American McGee’s Alice
Alice: Madness Returns
Dustforce
Gish
Dark void zero
Bionic commando: Rearmed
Sideway
Mirror's edge

That doesn't look too bad, if it goes on sale on PSN again I might get it. I always figured it was some Pokemon-type game by the title.
Thanks I will try later tonight or tomorrow.