I was curious about the same thing. I watched tenjou tenge and I got 24 eps into it, only to find out they didnt make any more.. It made me SOO MAD. I thought it was very very well done, and would recomend it except for the abrupt ending.
Well, watch the OVAs (there are 2 i think) and you could watch the movie (no new material there though, it's basically a summary of the series).
Then if you still want more, read the manga. (But you're probably more interested anime than manga.. am i right?
well bloody devote all your time into getting up to date first! then think about other anime. Bleach has got to be the best anime series ever(after NGE).
Then after your up to date go watch NGE(Neon Genesis Evangelion), FMA(Full Metal Alchemist) and i've heard good things about cowboy bebop so give that a shot.