What do the following topics emerging from SXSW have in common?

1) Limited social networks

2) Group messaging

3) Geosocial

4) Tribe-targeting

5) Hyperlocal

These themes align around a common thread: intimacy. More than ever before, relationships are more accessible, abundant and constant. But relationships vary. Mainstream social sites we live on are geared towards aggregating and connecting with weak ties as much or more than strong ties.

Not surprisingly, we’re seeing more limited, private social networks emerging, exemplified by Path and its 50-friend limit. Group-messaging apps like GroupMe satisfy the longing to talk to – and listen to – only those people we count as true intimates. Network friends are one thing; intimate relationships something very different. Most don’t want to be famous to fifteen people. We want to be meaningfully connected to those fifteen people.

The hunger for connections with “people like me” is fueling momentum of tribe-targeted services; networks like Daily Pride, Gluten-Free Deals and Daily Deals for Moms. These niche, Groupon-inspired offerings bring together specific demographics, connected retail environments, delivered at a hyper-local level.

Established organizations should take note. Brands that enable that intimacy will have a lot to gain in terms of affection, loyalty, and revenue. Think less about luring people to follow your brand. More about drawing people closer to your brand as a result of drawing them closer to one another through platforms and experiences.

Deeper, more personal, more private communications are a big, underlying theme of SXSW 2011. Intimacy, not surprisingly, is looking to be the killer app.