Links to specific mammals have been provided in the species accounts or in the related articles that accompany the species accounts.  

Below are a few sites that provide more general mammal information, or cover animals outside of the Appalachian region. 

http://animaldiversity.ummz.umich.edu/chordata/mammalia.html This is the University of Michigan's Museum of Zoology's Animal Diversity Web page. At the bottom of the homepage, a listing of the three subclasses of mammals (monotreme, marsupial and placental) and all 26 of the orders are linked to pages with some good general characteristics of the orders and families as well as some very technical descriptions. By going to the homepage, Animal Diversity Web , and then clicking on "Kingdom Animalia", an excellent cladistic view of the evolution of life can be followed (similar to the University of Arizona's Tree of Life).  Details of many of the life forms are linked for more information.

http://phylogeny.arizona.edu/tree/eukaryotes/animals/chordata/mammalia/mammalia.htm  This site is a part of a massive website maintained by David Maddison at the University of Arizona called The Tree of Life.  This has a wonderful presentation of the lineages of all the life forms present on earth.  Starting from this page, you'll see the  three living groups and the three extinct groups.  Just below, you can click on the "Containing clade(s) link" to go to the ancestoral stock to these groups.  By doing this successively, you can go back to see where mammals broke off from the reptiles and birds, then the amphibians before them, and eventually, you can go follow the cladistics all the way back in evolution to the earliest life forms with the Eubacteria, Archaea, Viruses, and Eukaryotes (which included the protists, plants, fungi and animals). NOTE - At times, the first long website domain name will not work.  You will have a page telling you -you can't get there from here - but, in the middle of the verbage, you'll see "open link to" phylogeny.arizona.edu.  That takes you to The Tree of Life home page (the second link above).  From here, scroll down and click on search, and type in "mammalia".  That normally works.  Sometimes even that won't work.  I can't say why.  Don't give up!  Go back and find the "root" link.  This takes you to the beginning of life forms, as we know it.  It can be quite interesting to continue linking on each successive phylogenetic link of evolution that will finally take you to the mammals.  Claudistics can be fun!

In addition, if you scroll to the bottom of the mammalia page, you'll find numerous great internet resources.  If you get there.

http://www.ucmp.berkeley.edu/mammal/mammal.html  Created by the University of California Museum of Paleontology, a good start for general taxonomy/classification of all three living groups (monotremes, marsupials, and placentals, or eutherians).  Additional links to the different eras and epochs of geologic time provide some interesting reading.

http://www.healthsci.utas.edu.au/physiol/mono/Monotremata.html  For those interested in the monotremes, this site from the University of Tasmania tells you all about the echidnas and the duck-billed platypus.

http://www.nmnh.si.edu/vert/mammals/mammals.html This is part of the Smithsonian Institute's website.  You can browse the checklist of thousands of world mammals, or find the type locality of any mammal in the world, among other things.

http://www.animalinfo.org/anim_org.htm This is a site maintained by Paul  Massicot called Animal Info, that has a broad number of links arranged by organizations, specific species, and related links/publications.

http://species.fws.gov/ This is the US Fish and Wildlife Service's Wildlife Fact Sheets for many North American species.  These have been linked in my species accounts for the mammals of the Appalachian region.

http://www.enature.com/guides/select_mammals.asp  Based on the National Audubon Society Field Guide to North American Mammals. Great site with color photos and the option of sending photo ecards.  But doesn't have all of the species. 

http://www.neteze.com/ksholmes/naturetracks/ Gourmet chocolate animal tracks, fossils, slugs and more!  No, I'm not kidding.

http://www.nationalgeographic.com/infocentral/web/mammals.htm  This is the National Geographic website.  It has numerous excellent sites.  The best all-around for various-interest mammal websites.  Good work, Janet.

The Virginia Game and Inland Fisheries Commission has an excellent website maintained by the Fish and Wildlife Information System that provides general species information as well as specifics on the species within the state of Virginia.