The standard answer, of course, is a Maxim DS18B20. 3.0V-5.5V operating voltage range, digital, programmable resolution, available in TO-92, uSOP, and SO packages. $5.99 in ones from DigiKey, but can be had for under $1 per (shipped) in 5s on eBay. -55C to +125C sensing range, 0.5C accuracy, resolution programmable from 9 to 12 bits.
As a bonus, multiple sensors can be connected to a single line.
[quote]The TMP20 is a CMOS, precision analog output temperature sensor available in the tiny SOT563 package. The TMP20 operates from –55°C to +130°C on a supply voltage of 2.7V to 5.5V with a supply current of 4μA. Operation as low as 1.8V is possible for temperatures between +15°C and +130°C. The linear transfer function has a slope of –11.77mV/°C (typ) and has an output voltage of 1.8639V (typ) at 0°C. The TMP20 has a ±2.5°C accuracy across the entire specified temperature range of –55°C to +130°C.
The TMP20 4μA (max) supply current limits self-heating of the device to less than 0.01°C. When V+ is less than 0.5V, the device is in shutdown mode and consumes less than 20nA (typ). The TMP20 is available in either a 5-lead SC70 or 6-lead SOT563 package, reducing the overall board space required.[/quote]
There’s nothing available there with the sort of accuracy you’re looking for. Is something like an RTD or a plain ol’ thermistor an option?