Per Points, Miles & Martinis, Delta is selling five one-day passes for $99, or just under $20 each. They are only available in person at any SkyClub through December 31, 2011. Just reference promotion code 970211 when making the purchase.
That’s a really spectacular deal for anyone that thinks they might have a use for a SkyClub pass, given that this is a 60% discount. While there are plenty of ways to access SkyClubs (like the American Express Platinum card), having a day pass will allow you access to the SkyClub even if you’re flying on another airline.