Agreed! A thank you would be nice.

Or I love it when you help someone, and then they don't say anything at all. It's like they totally forget that you just helped them and that you're still standing there, waiting for some feedback. Their attention has totally turned to the computer, or the books, and they don't give you any leave. I find myself walking away slowly, backwards, quietly. Or, on the flipside, if I'm feeling sassy, I'll say loudly, "Okay then, let me know if there's anything more I can do!" And then they usually wake up and go, "Oh! Yeah...thank you..."