I have to admit that about 50% of the material I perform is humourous. This is because much as I like to see people smile, I love to hear them laugh.
I usually do folk-parody material from the likes of Les Barker or The Kippers, but I cover music hall songs as well. I'll usually build a set, (3-4 songs), on a theme and finish with the comedy material.

(I'm still working on The Audience non-Participation Set)

AndyG