Good idea: Posting a forum that’s amusing and will be fun to write for and pwn.

Example:

Hot Without Hair

The Hot Without Hair Forum is dedicated to supporting and celebrating life without hair. Perhaps you are a skinhead who is shaven by choice, someone undergoing radiation treatment, or even a person who is prone to alopecia. Join us and post pics of your shiny, hairless body or discuss bald and temporarily bald celebrities! We are working on setting up live chats with Natalie Portman, Sinead O’Connor, and Bruce Willis, among others. Be out and proud without your hair!

Topics: Celebrity, Tips and Support

Bad idea: Writing a bland forum idea that would be really, really boring.

Example:

Flogger

Do you enjoy erotic torture? Do you want to read about the bondage experiences of people all over the world? Better yet, do you want to tell people about your own experiences? Then come to Flogger, the blogging site for those interested in the art of BSDM! Our archives hold discussions ranging from whipping, erotic electrostimulation, spanking, dominatrixes and much, much more! So stop looking at that dated femdom video and come to Flogger today! And remember, the saftey word is “banana”!

Topics: Dominatrix, Torture and Bondage

It’s dangerously close to Homicide Girls, and so is not a decent forum.

Problem with OP: Humor is subjective.