Currently I'm not using any, however, I'm busy writing my own learners software, which I'm going stuff with useful features (no definite list yet). I've currently done about half of the program, which means the two dictionaries (kanji dictionary and compound dictionary) and one kanji lookup system (the one based on multiple radicals). I still have to add other kanji lookup methods and the studying part. After that it's nothing more then a cleanup op the code and gui, and the compound dictionary can be optimized for speed. And thats it. When the program is in that state, I can start adding features other people like to see.
I'm pretty confident that I can finish the program within a couple of months.
The program uses the .net 2.0 framework (and needs Win 2000/XP), and if anyone is interested, I'll see if I can make it available to the public before it's finished. The final program is going to be free software (gnu license).