You mentioned themes,
I put the Scroll Today theme from the below link on my 8900. I love it. Seems to fade between screens. Shows 5 latest calendar appts and 2 newest emails on homescreen along with about 9 homescreen icons.
I like the calendar because of the new scroll wheel for changing dates/times. Kinda like the iphone. And when you move an event to another day it goes to that day and shows you the event was actually moved. 4.6 just left you on the current day and you had to go to the new day to confirm the event was properly moved. 5.0 lets you set phone/message ringer profiles for any contact from that contacts listing in the phones contact list.
The Theme Zone: 3 Scroll themes: Scroll Today, Scroll Calendar & Scroll Plus (8900, 9600, 9700)
Ken