There are many people who ask for invites to sites that don't offer invites. This wastes time and creates useless threads. I've made this list here of sites that offer invites and sites that don't (if its not on the list doesn't mean that it doesn't have invites and the list can't cover everything) The list has sites that are asked about most often.
Post sites that i don't have on the list and I'll update it. Make sure you know if it offers invites or doesn't so i know where to put it. I can't check every site myself.
Sites That Have Invites:
Sites That Don't Have Invites: