Texas Instruments has just released engineering samples of a watch that is based on their MSP430 family of MCUs, complete with a PC-based IDE so you can customise it any way you want.
EZ430-Chronos - Texas Instruments Embedded Processors Wiki
I am a professor of EE at a community College near Toronto. Occasionally I get requests for suggestions for capstone projects.
If anybody is interested in helping to design the 'perfect' digital watch for their needs, perhaps you would like to pass on a wish list to me and I will see if my senior students can build it for you. Alternatively, if you can program in C, you can do it yourself. My email is nw.johnson (.at.) ieee (.dot.) org.
It has two main digital readouts and five buttons. An accelerometer is built in, as well as an altimeter, but alas they do not have a pressure setting feature in the software that comes with it. You can also use it to change slides in powerpoint presentations!
It has a wireless link to a PC using one of three ISM bands so you can connect it to various other devices.
Unfortunately I can't undertake any more projects myself since I volunteer too much!