Since Traci already plugged me, I will go ahead and add to the suggestions you have already gotten! The one thing you want to look for in any good carrier is how the baby is held. Just think of how you hold your baby in your arms, they are held in the cradle hold, or on your arms or hip, but in both positions thay are butt below the knees. You do not hold them by their crotch and let their legs dangle down. Having them in a sitting or cradle posittion allows for their spines to curve in a natural C positiotn, instead of arching back as they tend to do when you support them only by their crotch. Thier spines curved correctly is better for baby, and less strain on your back when you hold them in a carrier.
That said, the Moby is a Stretchy Wrap, essentailly a long peice of cloth that you wrap around yourself and baby. Great for newborns and little ones, but does tend to stretch a bit to much after 25 lbs. There are also a large variety of woven wraps out there that are supportive for heavier weights that would work great now also.
HotSlings are great pouches which can be used from newborn up. I LOVE the ease of a pouch, but pouches and ring slings are one shoulder carriers, so may not be as comfortable on your back for long periods of time.
Mei Tais (or Asian back carriers) are rectangle peices of material with straps on top and bottom (think of a really pretty print Snugli with wide support for babies bottom and straps instead of buckles). They can be used to carry baby on front, hip or back.
Someone also mentioned the ERGO. This is a great carrier for all ages, and if you like that "structured, buckles" look, is a wonderful choice. This is the carrier I use most right now (along with my woven wrap), I have a 16 month old whom I back carry, while 27 weeks pregnant.
thebabywearer.com is a great site to go to , but very overwelming at first, you will literally see hundreds of choices!! Best bet is fine some near to you where you can try on carriers to see what is right for you. So many people try wearing their baby in one type of carrier and don't like it and quit - like the woman who posted and said she did not like the sling "but may not have been wearing it right" - getting help from someone with babywearing experience can make such a difference! Oh, and you can wear your baby in most carriers so that they can see what is going on. Or find a NINO meeting near you (Nine In Nine Out - the Babywearing Organization), you can find them at www.nineinnineout.org.
If you go to my website (Traci posted it), and go to Types of carrier up top, you can see a good explination of the different types of carriers that are out their.
We are in Felton, DE - not sure where you live, but if you send me a message, I may be able to track down a vendor near you.
Good luck and Happy Babywearing!!
K.