plugin for manage own ad

hi!

im new (noob) wp user!

im looking for a plugin for manage my own ad in my blog!

im looking for a plugin that enable each registered user to post an ad! and this ads must be by category, a thing like:

– i offer job
– i look for job
– i sell house

and so on!

help me please! and excuseme for my bad english!

who can help me?