One of my servers was shutting down recently due to a faulty fan, so heat has been a raised concern for me. I just ordered some themometers from Newegg.com for some servers, and installed a ventilation fan in the server closet at my office.
I'm also interested in power consumption, and so the idea of using mini-lcd displays for output of important information is attractive to me. Thankfully, someone else felt similarly and came up with LCDproc for linux. The vacuum flourescent displays look much nicer, but I expect they'd use more power.
As an example comparison: * VK162-12 from Matrix Orbital uses 9ma - 160ma of power ($70)* LK202-25 from the same uses 5ma - 107ma ($60)
When I checked out those features, I realized these devices also have RS232 interfaces!!! That is so cool. I guess they are powered by USB but controlled by RS232 (serial).
Not sure which one to get yet, the prices seem too high compared to what I'd expect. The temp gauges I bought were only $4.99.