Here are some cool sites to check out:

http://www.indy500.com/ The live streaming video on the front page is awesome, and the audio is good too!

http://www.joost.com/03600cn This is an incredible website. Download the program, and you get hundreds of free shows. The IRL Channel and the Indy 500 channel are MUSTS if you are a 500 fan.

http://www.indycar.com/ The series website with great features.

http://www.tracksideonline.com/ There is no better website or news outlet covering the IRL.

http://www.trackforum.com/forums/index.php? This is where you can find TONS of racing gossip.

http://racefanradio.com/ A fanastic radio website for racing.