will they let you off the plane with a one way ticket and no permanent residence status?
i'd be very surprised if the customs people would let anyone in like that, actually.
if i remember correctly, if you come for 90 days, you're on a tourist visa which, if i'm not mistaken, requires a ticket out of the country. otherwise, how do they know you'll ever leave?
my visa wasn't issued when i came over here the first time, but i can't remember if i had to buy a round trip ticket and just throw it away after getting the visa... it's only been a few years, but i'm hazy on this one. but just as Psy said, there's some paperwork you fill out at customs and it asks where you will be staying and when you will be leaving. people who have resident status fill out a different form. so that leads me to believe i just threw away my return ticket.
i'm more familiar with the renewal process and status change process than the initial entrance one, since i've only entered the country without resident status twice and that was awhile ago.
on a (comical) side note, i knew a guy who came over on a tourist visa from the US. and stayed for 90 days doing freelance web design work over the internet. at the end of 90 days he headed to korea or china or something and came back a week later as a tourist. he pulled this off about 4 times in 2005-2006. on the 5th time they were like, "why do you have all these continuous back to back stamps on your passport? how are you supporting yourself?" he would have been facing deportation and a ban from the country for some time. i'm not sure how he got out of it, but he's still here (but working under legal visa status.)