I replied to this thread more than a year ago when I had my old Android phone. I have the Tmobile Mytouch 4g now, so let me make some changes.
First off Power Manager and Missed Call are obsolete. Android 2.2.1 now comes with similar utilities built-in.
This phone has so much memory I can install a ton of apps. With my G1 and Mytouch 3g you could definitely feel some lag when you installed too many apps.
Here are my preferred apps w/ some explanations...