Facebook's $1 billion bid to buy the Silicon Valley map darling Waze has reportedly fallen through, and COO Sheryl Sandberg insisted on Wednesday that Facebook isn't getting into proprietary Facebook mapping software. So how can the social network get in on the startup world's high-stakes space of the moment now that the perfect buy has vanished?

"It would be great if we could build an awesome map," Sandberg told Kara Swisher and Walt Mossberg at All Things D's D11 conference this morning. "But we're not going to do that." As too many tech companies learned by way of Apple's fumble late last year, making your own map app from scratch is a more difficult endeavor than Google ever made it look, so that's out. But Sandberg didn't deny that Facebook needs to double down on the location-based game: "We have to prioritize ruthlessly," she said, suggesting that Facebook might be looking for another mapping technology to scoop up. Here are a few options, all of which would be cheaper than Waze — and some of which might take the social network in a very promising new direction.

  • Glympse This app works more like a private version of FourSquare than a mapping app, but it has the kind of data that Facebook so badly needs in order to make its ads more relevant. Glympse allows users to send their mobile whereabouts to friends — without broadcasting that intel to the world. While it might not draw users the way a more traditional navigation app would, Glympse could be appealing to Facebook's craving for location data, if only to bundle up our real-time whereabouts with all of our other offline habits — and sell them.
  • PlaceMe This technology might verge on creepy if Facebook adopts it wholesale, but PlaceMe automatically collects data without asking for any check-in information or anything. The app insists it encrypts your location and doesn't share it, but the social network has enough trust issues that acquiring something akin to a stalker app might not be the best PR move. On the other hand, PlaceMe has even more of that location-based data it could sell off to advertisers. 
  • Playcez As Facebook grows in overseas markets, this Indian location-based startup might make sense for the social network. Playcez tracks the location of users, in aggregate, to recommend hopping spots to individuals, who happen to be in the area.

None of these startups, however, has the appeal of Waze, which is all about mapping, not just the data that comes with it. It's the Google Maps/Foursquare divide — and that's why Google wants in, too. Users have a compelling reason to give up their location (and therefore privacy) while using a navigation device, which has made Waze the darling of the Valley this Spring. It's natural, and Facebook wants us to share our most intimate details in the most natural of ways. So it's stuck in a bit of a bind trying to find the next best thing without dumping another billion on something that's not right at this moment, while eliminating the possibility of building its own. Remember when Facebook tried to create its own version of Foursquare with Places and shut it down in a year? It was too creepy to succeed. The social network still tries to get our wherabouts on record, asking "where are you?" or "where were you?" when we upload statuses or photos — but what it really wants is something more constant and seamless. Waze was just that thing.