Continental is running a bonus of up to 5,000 miles for first-time ticketing and 2,500 for repeat customers on their website. The bonuses are available with all domestic e-tickets purchased before Monday, August 6.
There is also an on-going bonus of 2,000 miles that they sent out postcards for back in June. I don't know if it's targeted only to those who received a postcard or if anyone can get it. It is also good for any domestic roundtrip purchased through the web site, Continental phone reservations, or a Continental ticket office.