This site from the maker of bagged concrete mixes has calculators for piers and embedded posts as well as details for anchoring bolts and connectors with concrete.
http://www.sakrete.com/projects/calculators.aspx
Cool tool.
Here's the updated link.
http://www.sakrete.com/products/calculators.cfm (http://www.sakrete.com/products/calculators.cfm)
This one is formatted for smartphones.
http://www.sakrete.com/mobile/calculators.cfm (http://www.sakrete.com/mobile/calculators.cfm)