I use Merriam-Webster's Rhyming Dictionary a lot. With a paper copy, you can look at other end-sounds on the same page to get cool partial rhymes. Rhymezone.com is useful in a pinch, but leads me astray into obscure and meaningless phonemes as often as it helps - and is noticeably lacking a lot of words. And both of them are evil in that, if you use them long enough, you will try to rhyme every word in a poem with every other. One particularly egregious instance in my recent memory would be an attempted rhyming once of watching, blotchy, debauching, fibonacci, hibatchi, vivace, swatches, (the) Koches, 'en pace', cocyx, and so on - after which I found myself laid out for three days with a strained lumbar, a clearer conception of my own frailty, and no idea what the poem was about. I wouldn't recommend it to anyone. You'll notice though that this poem (
http://www.poemranker.com/poem-details.
jsp?id=80478)only has five rhyming sounds, and this one (
http://www.poemranker.com/poem-details.
jsp?id=79687) only has four if you count partial rhymes like 'Carly' and 'early' as one.