Found this site and hadn't seen it mentioned before. It has various SRS flashcard lists which are net-based and iphone/itouch based. According to the site, you can syc your account between various computers and wireless devices. Also can be used by wireless devices offline which would come in handy.
It has vocab and kanji for all the JLPT tests, vocab for a few specialised areas and keeps track of your progress.
This is a new site and I think it needs work with the site layout and a few other things. But if they get a few small problems like this sorted out the site has a lot of potential.