VOX General Spanish Dictionary- The most complete Spanish dictionary on the market is directed by Paz Battaner Arias, a Professor of the Spanish language at the University Pompeu Fabra. The dictionary was compiled by a large team of experts representing all varieties of Spanish using the most up-to-date lexicographical methods
SeaThreePO utilizes Google's GTalk translation bots to provide a simple translation service. As the author says "Its translations aren't great, but would probably do in a pinch. They'll likely improve as Google improves its translation bots".
More about the SeaThreePO project you will find at: http://code.google