Tricked Out

I purchased a Palm Centro about 2 months ago and I feel like I'm not getting the most out of the phone. Is there some cool software that I should download like applications? I also want to customize it a little more. I am familiar with the Palm Centro sites but not sure about downloading various software. Another question. Say I delete some contacts from the phone. When I go to sync it will the contacts still be backed up on my computer or will they be deleted there too? I don't want to lose them just want to delete them from the phone itself.