Bank of America continues their annual Museums on US program giving away free museum tickets during the month of May 2007.
Bring your your photo ID and a Bank of America credit card, ATM card, check card or MBNA credit card, and you will receive free admission for yourself and a guest. Multiple museums from the following states are included:
Visit the Bank of America promotion page to see if your local museums participate in this promotion.
Source: FatWallet forums discussion (via WiredDeals)