Handbook of RNA Biochemistry
Roland Karl Hartmann, Albrecht Bindereif, Astrid Schön, Eric Westhof
This is the perfect addition to anyone's library who works with RNA. It covers all relevant areas, though it could have had a little more on RNA interferance, and related small RNAs. The only drawback (besides the price) is that this is a two volume set, so be prepared for a nice big bulky package to come.