Fire up your iTunes and subscribe to podcasts by these guys. If you don't have iTunes, download it free from apple.com.
PhotoshopUser TV with Dave Cross, Matt Kloskowski and Scott Kelby, and Bert Monroy's
PixelPerfect are two of the best podcasts available for photoshop tutorials. Both podcasts are very informative and entertaining.
Matt Kloskowski has one called
Photoshop Killer Tips. Each episode is usually under 2 minutes in length. Quick little bits of Photoshop goodness!
LayersTV is also great because it covers all the Adobe products.
Adobe Creative Suite Video Podcast by Terry White is another good one.
I try to keep on top of these, but usually don't have the time to watch them as they come out. I just have a huge cache of episodes available for when I do get some time! If you only have time for one, I highly recommend Bert Monroy. The man is just incredible when it comes to Photoshop knowledge and pure talent.