Comment and I'll...
o1. Tell you why I friended you.
o2. Associate you with something. A fandom, a song, a colour, a piece of fruit.
o3. Tell you something I like about you.
o4. Tell you a memory I have of you.
o5. Associate you with a character/pairing.
o6. Ask something I've always wanted to know about you. (Or else I'll just ask a random question. I reserve that right.)
o7. Tell you my favorite user pic(s) of yours.
o8. Tell you that you must spread this disease in your LJ.