Multiple routing protocols can be used in ad-hoc wireless mesh networks (wikipedia). Some are described in the Wireless Networking in the Developing World (WNDW) book (HTML version).

OLSR

OLSR, Optimized Link State Routing protocol (RFC 3626, INRIA HYPERCOM project, wikipedia), is a routing protocol for wireless ad-hoc networks.

OLSR is proactive, it runs a distributed election to choose Multipoint Distribution Relays (MPRs), which flood peridiocally the network topology (Mesh Networking with OLSR, in WNDW).

A popular implementation is the olsr.org OLSR daemon, with a link-quality extension (README) using an ETX (Expected Transmission Count) metric, making it a Radio-Aware OLSR implementation (RA-OLSR).

The Open Mesh project is developping an alternative to OLSR, called B.A.T.M.A.N. (overview).

AODV

AODV, Ad hoc On-Demand Distance Vector (RFC 3561), is another routing protocol for wireless mesh networks.

It is reactive, it creates routing traffic only when needed.

802.11s

The OLPC laptop project plans to use the upcoming 802.11s standard (wikipedia), see the mesh network details.

It uses a new routing protocol as default: HWMP, Hybrid Wireless Mesh Protocol. It is based on AODV for layer 3 routing and uses a modified Rapid Spanning Tree protocol for layer 2.

RA-OLSR was initially included as an optional routing protocol for the 802.11s draft, but it has been dropped because of extra complexity for the standard, with no added value. Though, it can still be used as a routing protocol, since the 802.11s specification allows optional routing protocols (without defining them).