Remember, an infant carrier is outgrown when there is 1" of hard shell, of the carseat, above the top of their head OR when they have reached the maximum weight for the seat, 20, 22 or 30lbs. When a child is in an infant carrier, the harness should be routed through the harness slot that is AT or BELOW the child's shoulders.
Graco SafeSeat-- http://www.gracobaby.com/catalog/product.aspx?modelNumber=8A00PSN&CategoryID=1 This seat will harness your child 5-30lbs and around 32" tall, so you do not have to worry about a new convertible seat for possibly some time. Graco boasts that it will hold up to 97% of 1 year olds! These do fit in the Graco strollers. It has 4 handle positions and can be in any of the 3 positions when installed in the vehicle. It is FAA Approved and you can use this carrier without the base.
Chicco Keyfit 30 (pronounced Key-Ko)-- http://www.chiccousa.com/product.php?productid=250&cat=3&page=1
This seat will harness your child 4-30lbs and around 30" tall. Has an infant insert that can be used from 4-11lbs. Handle must be all the way down when installed in the vehicle. It is FAA approved. You can use this carrier without the base. 3 harness slots.
Chicco Keyfit 22-- http://www.chiccousa.com/product.php?productid=1&cat=3&page=1 holds 4-22lbs and around 30" tall. I have found that if you have smaller children, this seat fits them really well. It is FAA Approved and the carrier can be used without the base. Handle must be all the way down when installed and being used in the vehicle. 3 harness slots.
Baby Trend EzFlex-Loc/Latch-Loc/Rigid Latch-Loc-- http://www.babytrend.com/ Harnesses from 5-22lbs and up to 28.5" tall. The base is pretty narrow and the carseat is really light.
Britax Companion--http://www.britaxusa.com/products/product_detail.aspx?ID=2 Harnesses 4-22lbs and 30" tall. What I really like about this seat is that it has the anti-rebound bar on the base. What is rebound? Think of how the carseat is installed in a vehicle. The front of the carseat is toward the back of the vehicle and the back of the carseat is toward the front of the vehicle. When you are in a crash, the back of the carseat compresses into the vehicle seat, then it rebounds into the back of the vehicle seat--towards the back of the vehicle. The Anti-rebound bar STOPS the carseat from going into the back of the seat too much. Britax just announced 9/2008 that they are discontinuing this seat.