Translation sites don't really work too well.  Words don't translate exactly from one language to another.  And a computer program can't really decide how to best put the words into a sentence.  Well, not yet anyway.  Thats why human translation ist he best.  But if you want a jist of how things translate, they work.  Just don't write a letter then translate it.  It doesn't work.  I translate a lot of stuff from german.  I find 
http://www.systran.com to be the best.
But I think what Coublacka_ is talking about is more along the lines of this:
http://www.unforgettablelanguages.com/i ... ench1.html
That is just a demo type thing.  You have to buy the product, but its more for if your just beginning the language.  I was thinking of purchasing the german one.  Other than that I can't really help you.
The only thing I can think of is a French chat room.  If you are fluent enough and just want to practice try that.