Also, If your commute is mainly in downtown or close in mixed residential areas, the classic bakfiet is a cool option. Didn't work for me due to distances, riding on city streets w/o facilities (higher speed vehiclular type riding), mixed surface trails, giant hills, etc. I have a couple of friends with them who love them. One is handmade here in austin and the other is dutch classic. These are also frequently used around our central city to haul compost and kegs of local beer.
http://www.mydutchbike.com/bicycles/bakfiets-trike/