In yet another push to gain market share in Seattle, Delta is running a promotion in partnership with Hertz to gain new SkyMiles members. While this offer was targeted to the Seattle Hertz location, it appears anyone can receive 1,000 bonus miles just for signing up.
In addition to this offer, Delta is still offering new members the opportunity to earn up to 40,000 bonus miles as well. The up to 40k offer gives new members the opportunity to earn bonus miles for completing various activities. For example, you will earn 5,000 bonus miles for your 1st round-trip paid flight and 2,500 bonus miles for each of the next 4 round-trip flights after that. You can read more in my post from January, New Delta SkyMiles Members Earn Up to 40,000 Bonus Miles. You must register for this promotion within 30 days after you enroll in SkyMiles.