the last couple of filler arcs of naruto havent been to terrible.
It kind of depends on your likes/dislikes, i havent found anything that could compare to One Piece/Naruto(non fillers)/Bleach.
Rurouni kenshin wasnt bad(i'm sure youve seen this)
Samurai 7 has been pretty good(although i still have a few episodes left)
Trigun is good(i'm pretty sure everyones seen this)
Elfen Lied was pretty good(GORE GORE GORE!!! and nudity, just a warning)
Gantz was ok(once again EXTREME GORE! and sex super violent)
Ive heard that Law of Ueki is good, although i've only seen the first 8 or so episodes
Eyeshield 21 is good, although the fansubbers that were working on it just stopped at episode 48.
Full metal alchemst(once again i'm sure you've seen it) was good.
Thats most of what i can think of right off the top of my head, if i think for a little while longer i'm sure i could triple that list…