iTunesHelper is what launches iTunes when you connect your iPhone and iPod.
Googling "Airport Base Station Agent" finds this:
TidBITS Networking: AirPort Base Station Update Tweaks Admin Utilities
"AirPort Base Station Agent provides monitoring of base stations on the network."
Why do you have Airport Extreme Base Stations if you're not actually using Airport (=wireless LAN)?
Intriguing question, though not strictly relevant to what you're asking.
A rather more interesting exercise is to open Activitiy Viewer and see if they're actually using any resources at all as they sit idly in the background. Chances are, they'll suck up 0.0% of your CPU power, in which case:
They don't bother you, and there's no reason you should care. Leave them alone.