The other thing that I'd like to point out is that we can all LEARN how to spell obsessed correctly.
Sure, some of us might have difficulty, particularly those of us who don't speak English as a first language, but I have confidence that everyone can get it.
After all, it's no harder than some of the user names we've picked.
I have a friend on LiveJournal whose user name is nuingiliath. We've been friends for years and years now, since before either of us got an LJ... and when she first got her LJ, I had SO MUCH trouble spelling her user name. She was constantly commenting in entries or IMing me and saying "Honey, that's not how you spell my user name." I swear, every time I wanted to reference her in an entry, I'd have to open a separate window (as this was before the wonders of tabbed browsing) and look at my user info to copy the spelling of her user name if I wanted to get it right.
And then one day, I just typed it and after I posted, I realized that I hadn't checked it, but it looked right so I clicked. Lo and behold, it took me to her journal. I'd learned how to spell it without even realizing it.
So while people might type "obssessed" or "obsesed" or "obssesed" on public computers for a while, they'll eventually get it right... and then they'll be all gleeful and happy 'cause they learned something new.
Or maybe that's just me and I should probably stop posting while on the medication.