Indoor Aeromodelling covers all from good old RTP (Round The Pole ) to anything small enough to fly indoors without causing catastrophic damage to the model of course.  
Here we have a "Falcon Models Breeze Block" receiver, servo combo, this is used for indoor model aeroplanes this equipment can be found here http://www.falconmodels.uk.com/acatalog/index.html micro gear for indoor R/C

Check out these RTP links

Jetex Resources

Ballard's Shop - Full line of RTP supplies (UK)

Peter McCarthy - Pole and cardboard model plans (Australia)

R.T.P. Electrix - Kits, Motors, Accessories (Australia)

Dan Mosgaard - Pole and plan plans (Denmark)

Electric Round the Pole Fliers - RTP history

 

Checkout this link for indoor r/c gear

http://www.cleanswing.co.uk/accessories.htm