What you may have seen are the fairly high-rise stems on BT frames (or Kogas -- same bike, different paint). BT's have a very short head tube so you need a good bit of rise on the stem. The frame takes a standard 1" stem, so you just look for an MTB stem that has the right dimensions, and it'll fit 25.4 track bars as well. Those bikes have particular stem needs -- most other track bikes don't need such a high rise on the stem.

If you want a custom stem, you can get a lot of manufacturers who will make them for reasonable prices. Call John Dacey at www.businesscycles.com about a fillet-brazed steel Landshark stem custom to your dimensions. He made one for me for about $125. Salsa used to make the nicest custom track stems out there, but I've heard they discontinued the custom stem business. Builders such as Strong and Waterford regularly make custom steel stems, and you should be able to get one like you want from Dave Kirk (www.kirkframeworks.com) as well. David is the best -- he used to be the steel frame builder for Serotta and does absolutely magnificent work.

The Nitto stems pictured above are nice, and very reasonably priced, if the measurements work for you. There isn't much flexibility in dimensions. There's also the Deda Pista stem, which has a pretty good drop and works with 31.8 mm oversize bars. The only drawback to the Deda is that it's relatively light aluminum with Ti bolts -- you be the judge whether you need a super-strong steel stem (like the Nitto) or do fine with an aluminum one.