you don't have to threaten to leave to get a raise; you talk with your manager and tell him what you think you're worth and why its important to you that you make that, and you have a conversation about it. maybe you haven't demonstrated that you're worth it (go get a blog, speak at a user group, go earn your credibility). maybe the organization doesn't value talent at low levels [1], in which case you'll never get top compensation.
