This thread is very useful, and its nice to see a gallary of nicely built locos.
Here are some whitemetal kits from my collection to add to the list:

A pair of Peco Glyn Valley Tramway engines, built by my much missed friend Gavin Lowe.

A built up GEM varikit

A 40hp Armoured Simplex, not sure whose kit this is.

and a Hunslet, again, not sure who the manufacturer of the kit is but its a nice little runner.

Next on the agenda, a Vale of Rheidol railway loco.

I also have this kit, it appears to be a steam loco with skirts over its wheels, but not sure what manufacturer or prototype it is.
Also in my collection, but not a kit:

This is a Hudswell Clarke built by Paul Windle, seemingly out of platicard. Looks fantastic and runs well.

Looking like a beached whale due to a lack of monorail track at home, my scratch built Listowel and Ballybunion Hunslet monoloco, as seen in Model Rail December 09!