Lately I've been noticing more uncommon heterographs. I can kind of understand the there/their/they're problem...two of those words are not nouns. (Although I also think that with a moment of thought, it is easy to figure out the correct one.) Here are the ones I've seen, with made-up sentences...
"I maid the program last night, so it should be all set." (This one really surprised me and it took me a while to figure out what was going on.)
"I finished the hole thing."
"I took the forth train." (Actually, I think I spelled this wrong earlier, but I've since fixed it.)
Isn't language interesting? What are your favorite heterographs?