I have been using Adobe Lightroom for a couple of months. There are plenty of lists of shortcuts around, but they tend to be too long to be useful. The most useful one I have found was in the back of John Beardsworth's book - Adobe Photoshop Lightroom: Digital Photographer's Guide. I have had to search about for a couple of others so here is a table of some useful keyboard shortcuts that I needed.
|F2||Rename selected file names|
|X||Mark selected images as|
|ctrl+G||Stack selected images|
|S||Open or close selected|
stack of images
|alt+0169||Code to insert “©” into copyright|
|G||Switch to grid mode|