The only thing I could see right now is some more eye candy like HTC's sense UI. Even that is not really needed but it would be cool to mess around with. Might have to pick up an Eris just as a second device.
I totally agree with this (as you already know, ha-ha). Many of the widgets in the Sense UI are - sort of - available through the Marketplace, but they aren't nearly as nice. And I have yet to find a calendar widget that works well with the Corporate Calendar app.
I also agree with the spell checker. This is a must have when I'm responding to work emails. The spell checker doesn't even appear to be an option when using the physical keyboard.
Last but not least, HTC introduced a few business oriented features in the TP2, that I would love to see on the Droid. The main feature having to do with the way the calendar and the phone integrate. For example, on the TP2, when a calendar reminder pops up, it pops up with a big button that I can push to dial the con call #. It dials the number and takes me to the phone screen. From the phone screen, I can push an icon that opens up the notes for that calendar event, which typically contains the access code for the conference call, so I can enter that information into the dialer and join the call. I never leave the phone screen in the process. Without that, I'm switching back and forth between the phone app, and the calendar app trying to get the code. This is a feature I've always wanted on every phone and they finally did it in 2009.
I would also like bigger contact pictures in the phone dialer screen, and to be able to narrow down contacts as I dial letters in the phone dialer screen.