Probaby the best thing for you do is to have the bikes overhauled about once a year or every 3000-4000 miles. What that SHOULD entail is a complete teardown of the bike, cleaning and regreasing of all bearings and hubs which should include the headset and bottom bracket. replacement of the brake and shifter cables, inspection of the handlebars, frame, and aluminum parts for cracks or damage, and trueing and tensioning the spokes. Of course clean or replace the chain as necessary, clean the cogset and chainwheels. Clean and lubricate everything else that needs it. I am amazed that you are getting away with only replacing your chain if you have 3000 miles on your bike. If you have a proper overhaul performed you bike should ride like new. Generally an overhaul can cost from 135 - 200 dollars. But you need to ask what they do and them write it out. The term overhaul means different things to different shops. Also you should buy a book such as Zinn and the ART of Road Bike Maintenace or the MTB equivalent whatever the case may be. That way you will understand what the shop is doing and why. A a former bike commuter I can tell you that one day on the way to work someting will break, and when it does, you want to know how to get going again. My old boss was none too keen on my commuting either. Now I cannot find a safe way to do it. I have tried twice but I have to cross a bridge and use the interstate to get to the other side of a river, its just too congested with no shoulder.

Take care of the bike.