Website Bot (Simple) NOT MYSPACE

I need a bot that will log into a website. its will search and display the members by the zip code selection. then it will allow me to send a the same messege to each person in that list. I can do this by hand but it takes forever, so I need someone to write a script that will run on a mac using OSX. Let me know who can build this quick. I had a .tcl script that I was using but suicidegirls changed their code so it doesn't work anymore..