What are some good nicknames for a crush?

[Erika]

There's this guy that i like, age 24, who sends me messages on Facebook with some sweet nicknames like: lil lady, lady, sweetheart... I don't usually know what to say so i just either ignore it, send a winky face, but that seems kinda lame. I want to say some sweet things in return but i can't think of any. I don't like being called babe/baby or calling anyone by that.
Are there any suggestions?

Just remember, we're not going out but i have a pretty good idea that he likes me, since he puts his arms around me when we walk, he leans into me when we sit beside each other on a bench and he sometimes drapes his arms over my shoulder.

Oh and besides... Valentine's day is coming up, should i get him something? Or should i just wait until he asks me out first? He hasn't even given me his number yet or asked for mine.
I forgot to mention that he has a girlfriend but he's told me he doesn't think it'll go anywhere... he's just giving it a couple weeks. He's also hinted to me that he'd ask me out.