Tough to beat E.S. Posthumus for sheer ear candy. Sorry, videos don't exist, but they are one of the most often copied artists for action movie trailers.
Although I think the singer is a bit freakish to watch while she's singing, (What's with that psycho stare?) I think Pomplamoose does some pretty inventive cover versions with interesting non-standard instrumentation.
Pretty cool video by 30 Seconds To Mars. (No it doesn't make any sense to me either...)
Laibach is another band that I think does great covers. Often the only resemblance to the original is the lyrics.
Currently the band that I feel is making the best music videos out there. OKGo. (And talk about videos that would be a serious pain in the butt to make...)
And the marching band version.
Cool stop motion video. Talk about a pain in the butt to try to lipsynch this one when it's comprised of individual photos chained together.
And and oldie but goodie from the band.
And a classic video from the 80's from one of my all time favorite bands, Yello.