For what seems like an eternity, Pollstar has been the main source of music tour and venue information for “folks in the know”, but there a few new kids on the block now who I thought you should be aware of.

Jambase – An upstart competitor to Pollstar (a little less comprehensive from what I can tell).
Tourfilter – City by city tour info.
OnTour Desktop Widget (Powered by Pollstar) – A cool desktop widget that lists upcoming concerts in your area based on your iTunes library.
iConcertCal iTunes Plugin (Powered By Jambase) – A cool plugin for iTunes that lists upcoming concerts in a calendar format as part of the iTunes application.
(The aforementioned) Pollstar – Aside from its decent search features, it’s worth noting that Pollstar will let you set up two free alerts (based on venue or artist) if you have a basic account, (even more if you pay).

There are also a few good blogs/websites that provide useful information on tours. When I get the urge, I will check out:

More Cowbell – A MN based blog with lots of tour dates.
Concert Joe – Concert Joe’s site is Old School, but he does have a lot of NYC listings.
Upcoming.org – Gotta love Upcoming.org (now a part of Yahoo!).
Oh My Rockness – The concert site for hipsters du jour (the newsletter is definitely worth signing up for).
Myspace.com – I know, it’s a no-brainer. But often bands list upcoming shows on MySpace before anywhere else. It has a terrible search, (which is actually an improvement over the old one), but if you dig you can get some good info.

Also, I suppose I should include the Corporate Honchos, because sometimes, “ya gotta do, what ya gotta do”. Your three main ticketing sites are:

Ticketweb.com, Ticketmaster.com, LiveNation.com – Yes, I know, these are also no-brainers, but once again, if you dig deep, there is information to be had (LiveNation also now has venue RSS which is kind of cool).