I am currently using delicious because I was worried about hitting the LJ character limit for a post... eventually. =D Dotfic and Velvetine01 also use delicious for their masterlists and I find them to be super helpful, especially for Dot's work because she's been writing for so long and writes in several fandoms. Delicious lets me sort for things v. quickly. I am pretty sure delicious is safe now that Google is looking at buying it (you can even make a new account and sign into it under your gmail address, which I just love), but Diigo allows you to import and export delicious bookmarks. I am thinking about using it as a "just in case" back-up as well.

I think Halfshellvenus uses a master post of master posts which I found really helpful, again, for sorting via fandom, etc.

I don't think you can go wrong as long as you have something up, you know? I am reading this incredible writer at the moment who has been writing fan fic for a decade and she only has her fic organized by tag. It's a lot more difficult to follow and locate things. :/