Swarovski have partnered with someone to offer up this USB engagement ring. There even appears to be two different models, but this ring would allow you to carry around a certain amount of data in your engagement ring.
It could be pictures of you and the one who proposed, or vice versa, or poetry, or pictures/videos of other good memories of the two of you, or it could be important documents you need for work. The coolest implementation would be if it were the key to unlock a new computer you were also gifting your special someone.
Regardless, it’s an open platform for a geeky proposal if you don’t have the creativity to create a new iPhone commercial hack a Nintendo DS to do your proposal for you. Sadly, it’s actually just a design, so it’s a no go on actually doing this, but one cool feature is that two rings can dock with each other to sync data, however that’s done.