1) Custom BBCodes would be nice...
2) Post seperation would be nice, too. Like in vBulletin (I had to add it to ipb), have it like:
----------------------------------------------------------
*bar with bg* Date
----------------------------------------------------------
Author Info | ____post title__________________________
|
| User's post goes here, etc....
|
You know how it goes.
Custom BBcodes may make it into the next feature update of SMF (After 1.1).
As for the second suggestion, that is fairly easy to do with a simple change to the display template in the theme.
There's a mod by me for custom bbcodes. The look of posts you can modify in a custom theme made by yourself, look in the Graphics and Templates board for help if you need it.