Hiragana and Katakana Practice — Real Kana
Realkana is a website I stumbled upon by accident really, but I have used it a lot to practice remembering the different kana.
You can also choose the kana that you wish to practice, weither you only want to practice half the hiragana, all the hiragana or katakana or both, if you get a kana that you don't know or can't remember you can move your cursor over the symbol and it will tell you the correct romaji, and also how many of your answers have been correct or wrong.
Unlike some other sites I've seen where you get options to choose from, on realkana you have to write the romaji yourself, which makes it a little harder.
I think that's about all that I can mention right now, so.. the end.