IM etiquette

IM is the worst but I use it everyday to make life easy (plans, iTunes swapping with pals, instant gratification, linkage, etc). Yet sometimes its like having your annoying neighbor knock on your door because they're locked out and you begrudgingly lend them your phone. I need to stop being such a wuss about my IM space bubble and just start blocking people. I've said this before: its like a tiny rape every time I log on.