No problem
Airio and Lapper are the ones I come across usually, and there's also PRISM.
Airio is pretty complete for admining and laptimes, but it's old, no longer supported and doesn't do scripting (airio.eu). Lapper and PRISM are more 'scripty' and flexible, actively developed, and they've both got dedicated forums here in the programmer's section.
Check out "9397 Racing" server for an example of Airio, and "Sin'rs Race N Drift" for an example of Lapper.
Edit: Doh! Those servers aren't demo. "![AMG] GTi MotorSport" is a demo with Airio, but I don't know any demo servers with Lapper or PRISM I'm afraid.