Do you mean particles like さ and し (sentence particles that took me a long time to find), or actual suffixes like 的 and っぽい? Or maybe conjugations?
Japanese particles - Wikipedia, the free encyclopedia is as good as any you'll find online for the former, although you'd be better off with a good grammar book.
Tim Sensei's Corner - Japanese Verbs - Introduction and Table of Contents is good for most conjugations. My only regret is it's in romaji. But again, you want a good grammar book.
I thought Jisho had the actual suffixes in it, but it's down right now (my heart...)