Here are a few that I saw on f1racing.net
23-25 February
Silverstone
17-19 February
Imola
10-13 February
Jerez
4-5 February
Silverstone Jordan, Jaguar Racing?
2-5 February
Barcelona BAR, Williams, Ferrari F2003GA, Sauber, McLaren
There is a thread about going to see Silverstone testing
here.