Here's a hotplate which can easily reach over 400°C, suitable for soldering PCBs etc. It just consists of a 7" 1800W cooker hob element attached with a vast number of screws to a 20x20cm piece of 6mm aluminium plate. A K-type thermocouple is attached to the center of the plate to measure temperature and a PID temperature controller regulates everything. Uniformity is very good, I'd guess within 10°C across the plate. I've used it for reflow soldering of PCBs, curing epoxy resin, glue etc.
05/12/13: I later made a frame and added a cooling fan - see here.