I came across a site for writing competitions: you may like to have a look at Sally Quilford's Writing Competition Calendar.
The Winning Writers site is another useful resource for writing opportunities.
For those who like Haiku, take a look at the Australian Haiku Society. The site lists a number of contests. On the subject of Haiku, you may enjoy Tiny Words.
This is not a competition, but take a look at the readwritepoem blog. .
This is a competition: Grist. Judge for poetry: Simon Armitage.
The Caroline at Coastcard Blog counter is now registering 1000.
P.S. It was good to be reminded that Michelle Lipman won the Bath Spa Poetry Competition some years ago with a 3 line Haiku. When it comes to poetry, the right words in the right order can count for more than the quantity!