S.O.S. Mathematics (http://www.sosmath.com/)

For "high school, college students, and adult learners," SOS serves as both refresher course and introduction to new material. Although the information and exercises on the site are limited and the site does include annoying advertisements, S.O.S. is a worthy Web site.

Hacking Mathematics (http://www.math.fsu.edu/~wooland/hm/hm.html)

An online textbook for a liberal arts mathematics course, this site offers students the opportunity to gather information and complete corresponding exercises.

r /> Project-Based Instruction in Mathematics for the Liberal Arts (http://faculty.uscupstate.edu/mulmer/PBI_Index.shtml)

This Web site is not easy to navigate or to look at, but the quality and range of content are admirable.

Mathematics History (http://library.thinkquest.org/22584/)

Unfortunately bogged down by poor Web site design, the Thinkquest-sponsored site is filled with useful information about the history of mathematics for non-math majors at liberal arts institutions as well as for students in more math-centric academic programs.