I usually title mine when they're done, fyi.
Now sometimes, with me, a title will just be obvious. Like say with the story Caught, because in it, Lex catches Clark wanking then Clark catches Lex wanking and the final line is "I'm glad I caught you" or whatever, so yeah, BINGO. I've got me a name for my fic! I like stories where a word will spring out at me like that, and you'll note that a lot of my stories have one word titles. Drown in my deepness.
But then other times, I'll stare at the story for ages and NOTHING WILL COME TO ME. I'll reread it in the hope that I'll see some hidden meaning that I can twist into a clever title, but then I'll be like, uh, there's no hidden meaning, it's just porn. And I can't exactly call it Porn. (One day, I might call a story Porn, just to freak you all out.)
So in cases like that, do you know what I do? Hee. I'll think of random songs that might (or might not, I don't care) be relevant and I'll either flat out name the story after the song, or if I'm feeling especially sneaky, I'll pick a lyric out and call my story that. I mean HELLO people, my last two fics are called "I Could Write A Book" and "Don't Speak" and dude, they're not the only ones - I've been doing this since my first story. Sometimes I think it would be neat to come up with a clever poetic title ALL ON MY OWN but when I try I just end up feeling stupid, and then I listen more closely to whatever music I'm playing right then and I go, is THIS song appropriate? I rule.