You probably shouldn't have a smartphone then, if your data use is that low. I pull between 2 and 3GB each month, and thats with little Pandora or Netflix.
Hahahah what? I'm sorry, but that's inane. Someone shouldn't have a smartphone unless they're pulling large amounts of data? That doesn't make any sense at all.
Take my girlfriend for example. She's had a smartphone for a few years now - a G1, and now a G2. She averages about 150 MB a month. And yet, she uses the phone all the time. Sure, some of it could be done on a feature phone - a lot of texting and emailing - but she also uses maps/navigation, OneBusAway, Kindle, and hordes of games, which are pretty much smartphone staples.
Heavy data usage generally happens via streaming...and believe it or not, there's a lot more to a smartphone than the ability to stream media.
Hell, I only use about 1.5-2GB myself, and the vast majority of that is from SmartDJ mixes and tethering to my PlayBook to watch TV.