Do you mean a seat that you can hang on a tree independant of a treestand? But you want to use it with your treestand to make it more comfortable? If so the only two I know of that have arms are the two listed below. I recently purchased one of the Summit seats and set it up at ground level it was very comfortable and its designed so that you are leaning back instead of forward. I have not used the Big Dog I just found it when I searched for tree seats.
Summit Trophy Chair
http://www.cabelas.com/cabelas/en/templates/links/link.jsp;jsessionid=PZQ3MEI0C4AENLAQBBJCCONMCAEFGI WE?id=0039255417537a&type=product&cmCat=SE ARCH&returnPage=search-results1.jsp&QueryText=trophy+seat&N=4887& amp;Ntk=Products&Ntx=mode+matchall&Nty=1&a mp;Ntt=trophy+seat&noImage=0
Big Dog Deluxe Tree Seat
http://www.sportsmansguide.com/net/cb/cb.aspx?a=446498