There are many resources on the web for learning about Lightroom. Sometimes it's good to go back to the source. Adobe has a few great resources for Lightroom users that you should add to your list of favorites. Here are a few.
Adobe User Forums
Users, Community Experts, Adobe Employees and others hang out over at the Adobe Lightroom Forum and help each other. This is an excellent resource for interactive exchanges of ideas and questions.
If you've spent any time at the Adobe Lightroom Forum then you've probably met up with Anita Dennis. Anita does some excellent work helping the community with Lightroom (and other applications). She presently runs an Adobe blog called Phosphors dealing with Lightroom, Photoshop, and Bridge. Check it out for some great insights.
The Lightroom Team over at Adobe also runs a blog called Lightroom Journal. Here is a great place to check to see what's going on with Lightroom and Lightroom development.
This site brings together the best tips, tricks, and support from around the web and from inside Adobe. Go over and visit the Photoshop Lightroom Help and Support site. There is a link from there to the online Lightroom Help System (which is also available from the help menu inside Lightroom). Instead of a static manual, this is living document with comments and questions from users. Anita Dennis and a team of Moderators keep things up to date and on point.
So next time you have some Lightroom issue you need help with, check out the source over at Adobe!