vzhaipd (scoyo's Virtuozzo/OpenVZ HA IP Daemon) is a set of mount/umount Container scripts for Parallels Virtuozzo or OpenVZ that will make sure a HA IP is always present on one of two or more Containers. You can think of it as the poor man's VRRP for Virtuozzo and OpenVZ Containers. Use it for general service availability, software load-balancer failover, etc.
Synapse is an ESB engine and XML router built completely on open standards. It is a mediation framework for XML messages and Web services that allows messages flowing through, into, or out of an organization to be mediated, including aspects such as logging, service lookup, performance mediation, versioning, failover, monitoring, fault management, and tracing.