Good board for DIY temperature control/readout
I've seen a couple of "buttons and LCD and thermocouple" kits.
If none of them are adequate for what you are working on, I suspect you could pick almost any "buttons and LCD" kit and almost any "thermocouple interface kit" and connect them.
(in no particular order):

== buttons and LCD and thermocouple ==


Adafruit: "A thermocouple datalogger based on the Arduino platform" and at Luke Miller's blog
Sparkfun Reflow Toaster Controller
(The Arduino controlled Espresso Machine sounds similar to what you want, but alas, it's apparently not for sale).


== buttons and LCD ==


Arduino shield LCD+buttons Portable MegaPalm
Arduino shield LCD+buttons
Parallax Propeller LCD UI Module
Microchip PIC LCD+buttons 28 Pin PIC Terminal Development Board
TI MSP430 LCD+buttons MSP430F449 Evaluation Board
ARM MCU LCD+buttons LPC2106 Terminal Development Board
EasyWEB2 Internet Development Board has LCD+buttons
Orangutan LV-168 Robot Controller
Orangutan SV-328 Robot Controller


== thermocouple interfaces ==

If you ever need to measure temperatures above 125 C (257 F), you'll need to use a thermocouple and a thermocouple interface chip.
(Thermistors and IC sensors such as the Analog Devices AD592 and the Maxim DS18B20 cost less, but generally can't handle temperatures above 125 C).


Arduino Thermocouple Shield
RepRap thermocouple sensor (controls the heater head for the right temperature for melting and extruding plastic)
Multidisplay project and Multidisplay video (measures various temperatures in an automobile engine)
flue temperature sensor
4-Channel Thermocouple Input Arduino Shield


(I've made this "community wiki" so others can add really good/cheap examples and trim out obsolete items).