What Black Heart said is true, but it shouldn't be a limitation.
As for me, I highly recommend the Rurouni Kenshin OAV's (Samurai X Trust, And Samurai X Betrayal)
As for me, I watched them before the series, and I do consider them a masterpiece. As a fact, I have not ever seen a single chapter of the series, not because I don't want to, but because I haven't got the oportunity.
I also recommend Ghost in the Shell, Ninja Scroll, and the Vampire D movies. But alas, hard to tell you something considering you like Cowboy Bebop.
Ah, let me think bout more and I'll recommend some more later.
But, regardless of your taste, I highly recommend RK OAV's because they're the hot §hit
