Invite him to join you for a low-key group activity: "I'm going to a house party next Saturday. Want to come along?" It is more casual than asking him on a date-date (e.g., going to dinner) but still conveys you like him.
Enlist his help. For example, if you're moving and he mentions great movers that he's used, ask him for his e-mail address so you can get the info. Later, offer to take him out for lunch or coffee as a thank-you.
Before leaving the bar, party, or wherever you met, say "I'm taking off, but it was great meeting you. Here's my number if you want to give me a call." Then pass him your digits. You're on your way out, so awkwardness is cut short.
Wait for an opportunity to arise naturally. Say the conversation turns to baseball. Mention a cool sports bar you've been to, and tell him "Maybe we should go sometime." He can follow up on your lead, but there's no pressure.
