S scale 1:64 - its the perfect size and delightfully idiosyncratic! Cambrian, light railways, industrial, narrow gauge and American shortlines. Also 1:152 2mm Finescale and 2mmNG, and some overseas modelling in 1:160 N scale.
I'll demo-ing with the 2mm Scale Narrow Gauge Group at NG Southwest, Whitstone School, Shepton Mallet, Somerset, BA4 5PF this coming Sat 16th Feb 2013. See ya there micro train buffs!