Some people use infrared ovens with fancy quartz heaters for their oven, and that's a great idea if available.  My oven was found on a curb with a broken power switch, so I used what I had.  It has only resistive heaters, which are slow to heat up and slow to cool down, not really ideal for a reflow oven.

To supplement the oven and increase the responsiveness, especially at lower temperatures, I added two halogen lamp holders (118mm R7S) and halogen bulbs, one on top and one on bottom.  For my implementation, I used two 500w lamps, which brough my oven up to nearly 20amps.  If you don't need as many watts, lower wattage lamps are commonly available, and cheap.  Be sure to get holders that have high temperature wires, some really cheap holders look like they have regular PVC insulation.

I made a bracket by bending a piece of stainless and drilling holes to mount the bulb holder and mount the bracket to the oven.  I also used 1/4" threaded inserts (rivnuts) for the wire penetrations to keep the wires away from the sharp edges where I drilled the oven.  Some sort of high temperature grommet probably would have been better, but the threaded inserts are working so far.  Theads were intact for all but one that I had to drill out because the wire insulation was catching.  After wires were fed through, the holes were sealed with high temp silicone.  You do want to keep some distance between the oven wall and the halogen bulb.

Why halogen bulbs?  They are commonly available and cheap.  They are also small and easily fit in my oven after fashioning some metal brakets to hold them in place.  Further, the cheap halogen bulbs are estimated to give off up to 97% of the wattage off as heat by some sources.  That's perfect for an oven. 

Don't you have a problem with turning the lights on and off continually?  Doesn't this shorten the lifespan?  Maybe it does, but again, halogen bulbs are cheap, so I'm not worried.  An argument could be made that running them in an enclosed space would keep the heat on the bulb more steady, and help prolong the life of the bulb. 

These bulbs worked so well, for my low temperature profiles, I use only the lower halogen bulb, all other heaters and bulbs stay off.