I think they should move the 3pt line back 2 feet and eliminate the corner threes.
It would play havoc with statistical comparisons though. Which would pretty much only affect autistic stats-loving people like myself. I'd still like to see it.
Half court 6 pt shots (but only in the last 2 minutes) would also be cool IMHO. If they bank off the backboard though, it's only worth the standard 3. If fouled in the act of shooting a 6, you shoot two FTS, each worth 3, regardless if the ball banks off the backboard (or misses entirely)
Also, if you are intentionally fouled to stop the clock, you should be able to decline the "personal take foul" and inbound the ball.
If you take off for a dunk behind the FT line, in the circle, it should be worth 6 pts. If you are fouled during a FT dunk attempt, you shoot two FTs, but each is worth 3.
For technical fouls, teams should have the option to shoot one FT, or one half court shot for 3 pts - because nothing is more boring than watching someone shoot a FT with nobody on the line.
If it is a technical for taunting or abusing the refs or embellishing, they should have 2 minute power plays a la hockey, and have to play 4 on 5 for two minutes (5th player can jump in and join the action when his penalty expires)
Dunks from behind the 3pt line, while impossible now, should be worth 20 pts. Get the kids practicing now.