Vermont Deadline: you may register to vote up to and including election day.
In another state:
The U.S. Election Assistance Commission allows you to download a National Mail Voter Registration Form (PDF) that is accepted in most states.
Alternatively (recommended), go to the website of the state agency that handles elections in your state. Access state election websites from the U.S. Election Assistance Commission. Most states have in-depth information on their website about how to register, the deadlines for registering, and have the official state form that can be downloaded/printed out and mailed in. Remember that you will probably need to request an absentee ballot as well.
Deadlines: The U.S. Election Assistance Commission maintains a calendar of state registration deadlines.
Caution: some states have much earlier deadlines than Vermont.
Resources for Voter Registration:
Can I Vote (National Association of Secretaries of State)
MiddVote (Middlebury student initiative)