If you are encountering a problem using R, you’ll likely to find a solution on the R help mailing list, online tutorials (A very convenient and easy accessible reference is Quick-R), one of the numerous blogs about R (see e.g., R bloggers, Cerebral Mastication, Recology) and the various other sources of information listed on the R website.
Still, it sometimes takes me time to find that little trick I need for this obscure problem I am having. And too often I know I have found the solution before, but can’t remember exactly where. So I started to keep a list with pieces of information I have needed at one point and may need again (using the fantastic Zim desktop wiki software). For others this is, well, just another list with entry points to a number of very helpful or otherwise useful web pages. You can find the list here.