CGEmpire is a relatively new site (kinda like www.cgtalk.com) however it's very small, personal, still and very helpful in game//art/music making.
They are having their third contest. One can compete in either form of pixel art, 2D or 3D (all in one division):
Winter Wonderland
They have included sponsors and prizes. The competition was announced 6 Dec , and the deadline is 31 January 07.
 |  |  |  |
 | Ash Wednesday 46 days before Easter Sunday (February or March) |
 | Easter Between March 22nd to April 25th |
 | Greek Independence Day March 25th |
 | March Madness March through first week of April |
 | Mardi Gras / Shrove Tuesday / Carnaval / Carnival Tuesday before Ash Wednesday (February or March) |
| | Palm Sunday Sunday before Easter |
 | St. Patrick's Day March 17th |
| More holidays | |