Researchers are social?!?!?

There seem to be two (at least) competing social media sites for academics and researchers out there.

Academia.edu
A couple of years ago, I stumbled on Academia.edu. I was trying to find an easy place to call my primary professional web home, and it seemed like a good fit. I liked its intuitive interface, built-in analytics (i.e., find out how many profile views and individual article views you've had (by country!), get emailed when someone finds your profile or paper), and a light social media component...no messaging, chat, etc, but you can follow colleagues and get a "news feed like" update on the work they post. I still use it and consider it my primary professional website. You can find me here: http://ucla.academia.edu/MattJans.

ResearchGate.net
Last week a Google alert sent me to ResearchGate. I joined only so I could reply to someone's question (I'm a softy for anyone looking for survey methodology textbooks), but as I was poking around I noticed that it has features for sharing files and collaborating. Light features...nothing like a complete online collaboration site, but more than Academia.edu. It also has a lot of "profile" features like Academia.edu, built-in analytics, etc. You can post your papers and talks here, (and I assume find out when people view them like Academia.edu...haven't reviewed or tested).

I also noticed that a couple thousand people from UCLA were already on ResearchGate, and there's some sort of campus-wide project on "computing uncertainty"...variance anyone? It's nice to have cyber connections with local colleagues! There's a very small presence on the UCLA Yammer page (Yammer was HUGE at Census...hopefully it still is). Here's my ResearchGate profile: https://www.researchgate.net/profile/Matt_Jans/?ev=hdr_xprf

A couple others...
I'm reminded that Sage started a similar site a few years back...I think this is the site (http://srmo.sagepub.com), but I wasn't able to log in. When it first arrived, I remember thinking that a) the site was very Euro and qualitative-heavy, and b) it felt like 85% of Facebook (some of the features, but not all of the features...I really just wanted its groups to be worked into Facebook) Thus, I never really got into it. If this is the same site, it looks like they've switched focus a little from being a social/prof'l hub for researchers to being more of a "research hub"...Could be helpful with group projects.

Last, and certainly not least is my favorite reference manager software, Mendeley  (www.mendeley.com). For  logistical reasons I mostly use Zotero right now, but I have it setup to sync with my Mendeley account so all my articles are in both places. Mendeley takes the notion of a desktop and web-based article repository and puts Facebook (the good parts) on top of it. You can create groups, share articles, etc. It's desktop user interface is superb, and it has a "watched folder" function that lest you drop PDFs into a designated folder and have them automatically imported into the software, metadata extracted and put into the correct (usually) reference fields, and synced to your online storage. (Aside: If Zotero could catch up on the interface and watched folder concept, they could actually rival Mendeley).

Here's my Mendeley profile: http://www.mendeley.com/profiles/matt-jans/. I started a couple of groups to share references with colleagues, but I have to admit that I don't use them actively. I've had mixed success bringing colleagues into Mendeley for various reasons.

If you have any favorite professional and research social media sites, please share! Also, point out the bad ones so I don't waste time signing up :) Thanks!