As someone who's job it is to obsess over iPods and MP3s, it's easy for me to forget that seeing a band perform live is really the ultimate way to experience music. I don't have the time or the money to see many shows these days, though, so I use the following video blogs to catch up on all the great live music I'm missing.
LP33.tv is one of the more curated video blogs on the list, and doesn't keep exclusively to live music (some artist interviews and polished music videos get thrown in, too). Content is edited together professionally and you're presented with a relatively broad range of independent artists from different music genres.
The Studio Sessions performance videos at NPR are more sanitized than the shaky live concert footage you'll find on other sites, but they're also more intimate. The audio quality is superb and so is the breadth and quality of artists they're able to bring in. If your tastes run more toward jazz, folk, world, and classical, then the NPR Studio Sessions are a great resource. They're also available as a podcast.
Pitchfork's indie music empire is best known for its in-depth music news and reviews, but the site also has a relatively deep selection of performances, music videos, and artist interviews. The artists skew more toward the indie rock vein, but the content is fun and I always walk away with a new band on my radar.
The folks behind The Take Away Shows have elevated the art of the live performance video. Each song feels like a miniature movie, and each artist feels like he was hand-picked from some magical record bin I'm not cool enough to know about. The site blends many genres, and performances are often intimate and impromptu. There are some very memorable moments here from Arcade Fire, The Shins, and surprisingly, Tom Jones (yes, that Tom Jones). Episodes are also available as podcasts.