Buying a Thermostat

[Will]

I was down at Home Depot the other day looking at Thermostats to put together an incubator for this year. I was just wondering if there is anything specific I am looking for,or is the 20 dollar base model adequate. I mean I know it would be cool if my Incubator could tell me when my furnace's air filter needs replaced or maybe there's one that'll do my taxes right now that could come in handy, who knows...? But I don't want to shell out more than I need to. I noticed some said Two-wire installation or something to that effect, some didn't mention that at all. Are they all the same as far as usfullness...? Anything else I should look for...?