Custom Silicon Solutions has come up with an ultra low power version of the venerable 555 timer. Typical operating current is under 5uA making it ideal for battery powered applications like one shots. It is pin compatible with the standard 555s and operates on supply voltages from 1.2 to 5.5V. I have tried just a few circuits with it and found it to be just as advertised so far. There are two versions, the CSS555 and the CSS555C; the second one has a built in timing capacitor which cuts down on one of the external components needed. The chips also contain a programmable counter which can be used to generate long timing delays. The CSS website has data and application sheets.