OpenVPN is probably the most popular semi-non-standard cross-platform VPN solution, with a large number of users and a pure userland implementation. It's pretty easy to set up, but I often forget certain steps so here's a tutorial for me to rememeber in the future :)
TCP Fast Open by Radhakrishnan, Cheng, Chu, Jain, and Raghavan is based on the observation that modern web services are dominated by TCP flows so short that they terminate a few round trips after handshaking. This means that the 3-way TCP handshake is a signiﬁcant source of latency for such ﬂows, and they describe a new mechanism for secure data exchange during the initial handshake to reduce some of the round-trip network transmission and associated latency for such short TCP transfers. This work shares many goals and challenges with T/TCP, which was previously in FreeBSD but suffered from some security vulnerabilities.
David Malone posted some thoughts on my Google+ post about how FreeBSD could implement the various changes. Maybe we could have some Summer of Code students work in this area this summer?
At a recent Linux users' gathering I temporarily saved the day when a WRT router was practically bricked, by setting up my netbook (Acer Aspire One) running 8-CURRENT as a wireless access point. It had wired connectivity to the Internet from one side and offered WiFi via its Atheros card on the other side. In between it did NAT and protected the LAN side from the Linux hackers, both with ipfw. Here is how I configured it.