In no particular order and suggestions for stock out-of-the-box, no app should be required.
1. Ability to customize color selected for email accounts
2. For the music widget: don't require a playlist be created for proper widget sync... It should pick up all you music unless you select a playlist (mine always says 'Selected playlist is empty' unless I select a song) Also add a Stop button for the music instead of just Pause...
3. More screens, allow user to specify number of screens desired.
4. Implement a smaller task bar like dxtop allows where you can have small phone, contact, messaging, etc icons for quick access and allow the user to select if they want them on at all times.. in an app or out of an app.
5. Have date show in notifications location when no notifications are present.
6. Remove the d-pad and use the extra space to make the hard keyboard larger.
7. Multitouch for keyboard and pinch-zoom.
8. Fix proximity sensor software bugs so no black out screens after calls... (mine stays blacked out every now and then...)
9. Improved camera software
10. Allow onscreen keyboard customizations (moving keys, adding/removing keys)
11. Allow user to define gestures for opening apps, calling people, etc.
12. Probably all on facebook, but fix facebook sync... not only does the widget suck, but I have some contacts that my droid thinks have 30 facebook inputs for their phone number.
13. Speech to text input for SMS/MMS.
14. Allow a quick way to mute all noises except for incoming calls and alarms... I'd like this for when I go to bed... I don't need to know when i get an email or a text at 4 AM, but if i got a call then... I'd want to know.
Thats all I can think of for now...
Just so you know, I LOVE my Droid and despite my suggestions here, I am perfectly happy with it
Also, just to point out, there are a lot of these customizations that can be done with apps found in the market, but its just always nice to have more features come stock.