1. What a pleasant surprise!
2. What brings you here today?
3. How's everything going?
4. Hello, there, what a coincidence!
5. Well, look who's here!
6. What's you up to these days?
7. It's really nice to see you again.
8. Fancy meeting you here! Small world, isn't it?
9. The very person I was after.
10. What keeps you so busy lately?