http://www.accessexcellence.org/AB/GG/mammal_Types_1.html
This is a downloadable chart discussing the 4 major animal tissue types. You can click on the companion page (types 2) to get some more pictures.

http://www-medlib.med.utah.edu/WebPath/HISTHTML/HISTOTCH/HISTOTCH.html
How are tissue slides made? This will explain in detail all of the steps in language that most people can understand. There are some interesting links as well.

http://www.marfan.org/
This is the Homepage of the National Marfan Foundation. One can learn about the condition in general or click on special topics such as eye care and aortic dissection.

http://www.neosoft.com/~uthman/blood_cells.html
There are some pictures of different types of blood cells here along with a links to several types of anemia.

http://www.ada.org/consumer/perio.html
Gingivitis is the disease of the tissue surrounding the teeth. This site comes from the American Dental Association and has some good diagrams as well as some things you can do to avoid gum problems.