PCB Manufacturers
UK
Screenbond 1 and 2 layer, low tooling cost, can do 24hr if you can afford it. Stickleback They have a prototype service via their Ebay shop
Online - worldwide
PCBCart Long established Chinese supplier, with wide range of options at good prices, even after shipping costs.
Eurocircuits Wide range of services, also stainless solderpaste stencils.