There are tons of companies making 'air ride' kits today, and quite a few make 'air struts' since a majority of the small cars have them on at least one end of the vehicle.
Basic kits probably suck, but I know there are some high end, complete kits that do things like self level, etc, and even offer IMPROVED handling! A basic kit won't do that... in a long hard turn, air can leak thru the lines from the heavily loaded outside bag to the lighter loaded inside bag making the car list over badly, like a ship! Expenisve kits cover those problems with more solenoids, valves, etc... I guess they even have ride height sensors of some sort.
Both of these cars use struts if I'm right.
[ame="http://www.youtube.com/watch?v=g3_udruti3c"]YouTube- VW MKV and Scion tC air suspension demo video Air Lift Company[/ame]