Egyptian calculator:
http://homepage.isomedia.com/~mjohns/calc.htm
Roman numeral calculator:
http://www.novaroma.org/via_romana/numbers.html
Cuneiform calculator:
http://it.stlawu.edu/~dmelvill/mesomath/calculator/scalc.html
Links to information on numeration systems:
http://mathforum.org/alejandre/numerals.html