Anyone will tell you the wisdom of "continuing to date" after you're married. But dating is expensive! I feel Jon and I have a practical understanding of the art of staying in (this also cuts back in babysitter pay later on)
1. First of all, make an inventory of things you like to do together (or learn together) that can be done indoors. Nerf ball wars? Learning foreign languages? Puzzles? Then invest in some of those items. *Note: Although movies are nice, remember very little interaction is expected, so reserve these for the "my brain is fried but it's only 8 o'clock and I don't want to go to bed yet" nights.
It should be noted that the reason I specify "indoor activities" is because we have kids and can't leave the house unless they're along or we pay for a babysitter (which either ruins the whole "date" part or ruins the "cheap" part). If, however, you do not have kids, then your range of motion widens infinitely. Shoot for the moon, y'all.
2. Indulge a bit! Remember you'd be spending way more if you were going out. So maybe break open a bottle of cheap wine, or stock up on treats you wouldn't normally give into for these special occasions.
3. Two-player games. If you're a board gamer, make sure your games are suitable for TWO players. Jon and I started out with tons of games, but they were all party games. We have begun to invest in games that can be played with 2 or more gamers.
4. Dress up or Dress Down. There's no law that says just because you're not going out that you can't get dolled up! In fact it's kind of nice to slip into a summer dress in January and sit down for a good logic puzzle or game of Yahtzee! Conversely, the joy of staying in is you can be in your jammies and sip your cocoa in comfort.


5. Don't forget about the "spicy games." Nuff said!
I hope this is helpful those of you who are either newlyweds or more seasoned veterans in the marriage game. Dating your spouse IS important, and it doesn't have to cost a lot of money to do it :) Please share with me YOUR creative solutions to dating on the cheap!
P.S. Jon and I are so nerdy. Some of our staying-in projects include learning Uzbek, doing crosswords and other brainy puzzles, planning trips, any of a dozen different games, and (recently) creating our own World-opoly board. No, you do not have to be as nerdy as we.