RH Designs Stopclock Pro for the enlarger. Expensive, worth every penny, accept no substitute.
For film processes I use my Palm unit and a wonderful free program called Foto Timer which remembers all the times and agitation patterns for different films for me and even warns me when an agitation is due. Much easier than a normal timer and highly recommended.
For the trays I use a sports stopwatch, half the price of a timer from a photo store and at least as good.