Vermont Castings made this type of stove for years. They're CAT stoves and allow you to top load.
www.vermontcastings.com

There are also some non-catalytic top loaders. We have a Quadra Fire Isle Royale and love it. The Harman TL300 and Lopi Leyden are others.

AWESOME forum BTW.. I love the fact that you've put woodstoves into your gardening and home forum.. love it..Thanks so much for putting this one up!!
My Husband and I also have a top loader. Very convienient! Of course you can always go to any Hearth store and look at them, they're everywhere, I'd go with them anyday for sure! We have a pic on Martys blog.. (my husband) of our stove. If you get the chance check out Martys Blog. See you soon Garden web! whoop

Here is a link that might be useful: DIY Cast Fireplaces

We had a top loading Vermont Castings stove for years and loved it. When I went shopping for a new stove this spring, top loading was one of the features that I insisted on. We settled on the Lopi.

Top loading allows you to easily load to the top of the woodbox and choke it down for overnight burns. Makes loading a lot cleaner too.

how much do LOPI's cost? I am looking to heat my first floor(small) 600 sq feet thanks for any advice!

Frank the only top loader that would heat such as small space would be the Vermont Castings Intrepid. Given all the drama that that company has had this year and the uncertainty of their continued viable operation I would stay away from that brand.