If you need help getting started or maximizing your use of Lightroom, AdvancedPhotography.net has a very nice article linking 10 free video tutorials. The tutorials cover most of the features of LR3.
Thanks Eduard. I'm still using LR-2 but most of the info still applies. I might add that Adobe has Lightroom-4 beta available for download. I'm using it in my work PC and so far so good. You can get it here if you wish Adobe Photoshop Lightroom 4 | photo management software beta - Adobe Labs