In addition to the Round-the-World promo for flights in and out of Washington, DC, United is offering a Round-the-World sweepstakes: flights purchased in and out of the DC area between June 15th and June 20th (short window!) earn an entry in the sweepstakes, and so will email entries:

If you wish to enter without making a purchase you may do so by sending an email containing your first name, last name, complete mailing address and telephone number to unitedaroundtheworld@eprize.net. For each valid email which contains all of the required information you will receive one (1) entry into the Promotion. Sending more than the allowable number of email entries will result in the voiding of all of the entries for that individual. Limit: three (3) entries per person or email address each day during the Promotion Period by any method or combination of methods of entry.