Hi Chuck -
I don't have a Centro, but I do have a Treo. There are tons of apps for the Palm OS. I would recommend that you get used to the Centro first, then see what it is that you think it's missing and go from there. It's easy to get caught up in all the cool software and end up wasting a lot of money.
That said, a good backup program is essential. I use Resco backup and have it set to back up my system daily. It's saved me on a few occasions. 4Cast is a good weather program, again set to update daily. Reset Doctor will log any crashes (which do happen on occasion), and Dial By Photo is a good add-on to the phone. I've got lots more programs but those are the "gotta haves" for me.
Hope that helps