I've written a simple IPhone app for timing long exposures accounting for reciprocity.

It uses a simple table format for reciprocity data that allows you to add your own films or tables you find on the net. I've include some standard b&w manufacture data along with some tables graciously provided by Don Kirby, Howard Bond and Bruce Barnbaum.

More info here.

App Store

www.davideisenlord.com/FilmTimer

Ike