http://www.thegmlenterprises.com/index.html
the above link to GML Enterprises. They mfg (in the USA) fast clocks and DC throttles. A number of local modelers use their clocks. You can have a bunch of digital outputs around the layout run by one master clock. They aslo do analog fast clocks I think.
I have used their throttles and their customer service and support has been superb.