The Serval Project is described as 'Serval is a telecommunications system comprised of at least two mobile phones that are able to work outside of regular mobile phone tower range due thanks to the Serval App and Serval Mesh' and is an app in the Network & Admin category. There are more than 10 alternatives to The Serval Project for a variety of platforms, including Linux, Mac, Windows, OpenWrt and BSD. The best alternative is Freenet, which is both free and Open Source. Other great apps like The Serval Project are cjdns (Free, Open Source), LibreMesh (Free), dn42 (Free, Open Source) and telehash (Free, Open Source).
LibreMesh is a set of modules extending the OpenWrt router distribution to create self-configuring wireless and wired mesh networks. By default it uses ad-hoc wifi networking and batman-adv, BMX as the routing daemons.
dn42 is a big dynamic VPN, which employs Internet technologies (BGP, whois database, DNS, etc). Participants connect to each other using network tunnels (GRE, OpenVPN, Tinc, IPsec) and exchange routes thanks to the Border Gateway Protocol.
Ninux is an Italian wireless network community with the goal of creating and expanding a free, open and experimental computer network. It uses the OLSR (Optimized Link State Routing) Protocol, an IP routing protocol optimized for mobile ad hoc networks.
SMesh is a seamless wireless mesh network being developed by the Distributed System and Networks Lab at Johns Hopkins University. It provides peer-to-peer connectivity, Internet connectivity, and fast handoff to mobile clients across the mesh.