To my mind, Adobe has some of the most extensive educational materials for their products of any producer I’ve seen. While I don’t find their large library to be all that well organized — I really do feel like I stumble upon some of their best stuff — what’s in the library is pretty amazing. I’ve just spent part of my morning going through the [Lightroom for Travel Photography](http://tv.adobe.com/show/lightroom-for-travel-photography/) series. Lots of great videos, ranging in length from 3 to 12 minutes, that give you insight into various features of Lightroom that you might not necessarily understand from working with the app in your daily workflow. There is also [Learn Lightroom 4](http://tv.adobe.com/show/learn-lightroom-4/) and [The Complete Picture with Julieanne Kost](http://tv.adobe.com/show/the-complete-picture-with-julieanne-kost/). And that’s just Lightroom 4.
Round Borders in Lightroom 3. Occasionally useful. Nice to have a tutorial.