for themes:
http://forums.crackberry.com/forumdisplay.php?f=177
http://www.pimpmyberry.com/forumdisplay.php?f=216
for apps i suggest you download blackberry app world:
http://na.blackberry.com/eng/services/appworld/download.jsp
what kind of apps are you looking for?
my favorites are:
poynt (free)
beyond160 (have to pay)
google maps (free)
facebook (free)
beejive (have to pay, but free trial is offered)
