not so much for swag and flow or diss type rhymes, but for those with a more poetic tint to their writing, I encourage you to check out:
sixfold.org
they have regular poetry competitions, with money awarded to first, second and third place (up to $1000). It only costs 6 bucks to submit, but you have to vote on a total of 18 poems over the span of a month (three rounds of 6 each, a week of voting per round).
Figured I'd share with you guys.
@
Vulgar @
zygote @
PancakeBrah @
Certain @
dead man @
Lars @everyone else that I can't think of right now.