I'd like to see a built in wet-bar, as Tony's always been more entertaining as a drunk. (See Ultimate Iron-Man vs. Current Asshole Iron-Man for examples).
How about a sprinkler. He could put out very tiny fires, cool himself off on a hot day (I'm sure he gets all kinds of sweaty in that suit), and water the lawn. Multi-purpose.
How about a printer attached to the suit that dispenses a mapquest (or google maps) location for eligible females (or males?) that displays the hotel and room number for that night's "Ironman and damsel in distress" play. A cat like Tony Stark should always be on the prowl in suit or out.
I like suit with a built in virtual hologram mirror. You have to look good when you're fighting crime. If you look bad then the criminals will just laugh at you when yyou're beating them up.
the xbox 360 glow ring on his chest, so when he takes to much damage it goes red, he has to get out and use the towel method on his suit to start it back up.