In response to Marcus, I've never personally experienced any difficulty from LiveJournal in relation to fanfic. Yes, I've seen some discussion about alleged hostility, but it mainly seems to relate to material - written and visual - including under-age sex, incest and other generally-held taboos - and I believe that it's due to fear of legal retribution.
LiveJournal a year or so ago started requiring users to flag journal content as suitable for all ages, containing some mature content, and as not suitable for minors. We're also required to state a date of birth when registering. If you're over 18 (or, for some mature material, over 14) and you're signed in, you see no flagging at all. Having 'grown up' in fanfic with our system of ratings here, where there's restricted access to nfic, I personally have no problem with LiveJournal taking steps to cover their own liability with regard to minors and adult material.
Overall, I find LiveJournal easy to use and it suits my purposes, though I did find it hard to navigate at first. Posting isn't as simple as posting to these boards, so if you do open an account there get someone to help you until you feel comfortable about posting more than just simple text.
Wendy
