I love these hacks! I question the logic to hack the cheap gear but this is more about artistry and 'climbing the mountain because it's there' rather than reason (or functionality). I mean, if you are trying to prove a point, then the cheaper the gear the more interesting the hack.
I've seen many ways to measure temperature with a DMM. One uses a bipolat transistor relying on the PN junction. Voltage changes with temperature. You do have to linearize in software. You can do the same with a thermistor. I used to have some code that worked with a 34401A to convert resistance to temperature in a PC.
If you ask around on the LabVIEW or VEE e-mail groups, you can probably get someone to send you their code.
I created a small interface board for my Mitutoyo Caliper (with electronic interface) to convert the signal to connect with a parallel port (LPT) on a PC. I then read the data directly into Excel. It was documented in my book "Excel by Example" Only availabale on Kindle now. I would be more practical to convert it to serial nowadays (I wanted to show how to connect to the parallel port back then).
Very informative article. I really liked the idea of converting digital DMM into temperature measuring device. Best part about all these ideas is that they can be easily realised with little investment. Looking forward to more such ideas.