The Australian Photographic Society, of which I'm a member, is conducting the Australian Digital Photography Awards 2009.
One great thing about this competition is, there's no cost to enter. Entries can be sent via the internet.
The competition will accept entries from residents of the Commonwealth of Australia and its Territories and from Australian Photographic Society (APS) members resident overseas.
I participated in the 2007 and 2008 competitions, and had some reasonable success. I've entered this year, too.
If you're interested, check the website and take particular note of all conditions and rules of entry.
Entries close on 21 June 2009. Highly recommended.