Hugh Lessig has this piece describing the distribution in Virginia by the NAACP and ACLU of "voter empowerment" cards, with this information.
The card says, among other things:
"If you are not allowed to vote because you don't have an ID, ask for an Affirmation of Identity form. You have a right to vote if you sign this form. (VA Code 24.2-643(b))."
"If you have moved since the '03 election, you should have notified your local registration office by now and received a new voter card. If you did not notify the registrar, you have a right to vote in your old precint in this year's elections. (VA Code 24.2-401)."
"If you believe you are registered but a poll worker says you are not, ask the poll worker to contact the local registrar. If the registrar is unavaiable or cannot find your name, ask for a Conditional Ballot. You have a right to cast a conditional ballot even if your name is not on the voter list. However, your vote will only be counted if the electoral board finds that you are currently registered to vote in that precinct. (VA Code 24.2-652-653)."
"If anyone challenges your eligibility to vote even though you are on the list of registered voters, ask for an 'Affirmation fo Eligibility' form. You have a right to vote if you sign this form. (VA Code 24.2-651-651.1)."