Que es VOM?
Also, when you say a bridge, is this a chemical or an electronic function?
Have you ever looked into the Vernier brand of measurement probes? They are designed for classroom use, and carry a "don't use these for real science" warning, but they are very easy to use, work with a lot of different platforms (win/mac, TI calculators, some old Palms), and have several components for adapting any BNC-type commercial probe. They are very "plug&play" and would be a logical choice for the home user, IF they are accurate enough for your purposes. They also have a very large installed base, lots of High School science teacher fans, and the company does a lot of work creating supporting curriculum, projects, activities and training seminars. You can also hook them up to Lego Mindstorms robot kits ! There are also software & hardware development kits. They are also reasonably priced. Jolly good fun.
One of the folks who advertises of APUG who sells a compensating developing timer (I think) uses the Vernier usb-enabled temperature probe in his design.