A dubstep mix retelling Jeff Wayne's musical version of war of the worlds, sampling the original narratives by Richard Burton, Phil Lynott and David Essex - http://soundcloud.com/erwtenpeller/war-of-the-worlds
If you like Knife Party, you might like the band's main project (Knife Party is a mini-project by two band members from a group named Pendulum.) They do fantastic drum and bass. Immersion, their most recent album, may be their best.
For Mashups collections, check out Bootie: http://bootiemashup.com/ (and if you're in SF, definitely check them out at DNA Lounge). They do a downloadable annual Best Of album. http://bootiemashup.com/bestof/ (IMHO, the older albums are better.)
If you're looking for a full-album experience, check out the Kleptones. Here's an awesome HTML5 visualization of their album A Night at the Hip Hopera: http://mashupbreakdown.com/nhh
I absolutely love upbeat electronic music and it's awesome to know I'm not the only one on Hacker News! For over six months I've been scouring the music blogs and accumulating a playlist on Spotify. I think you'll love everything I have in here - feel free to subscribe!
Many already mentioned by others, but also Madeon and Hood Internet perhaps? 2 Many DJs mixes. Oh, and look up Paris DJs and if you like a bit of variety check out the Molested Laura mixes, especially #6. DJ Z Trip too.
If you're looking for similar electronic music sets, here are a couple I've been digging lately:
Kaskade's set from Coachella, soundboard recording. http://www.themusicninja.com/live-set-full-kaskade-coachella...
Porter Robinson's BBC Essential Mix - http://soundcloud.com/edmtunestv/porter-robinson-essential-m...
Knife Party's BBC Essential Mix - http://soundcloud.com/edmtunestv/knife-party-essential-mix-l...
Luvstep 2.5 (There are several other mixes in this series, though this one is my favorite) - http://soundcloud.com/dirtysouthjoe/luvstep-2-5
Straight Bass to the Dome - Coletrain http://soundcloud.com/cberra88/straight-bass-to-the-dome