Shinken is a Linux/Windows monitoring tool in Python compatible with Nagios. The main goal of the program is to allows users to scale the load : it "cuts" the user's configuration into independent part and send it to workers.
See http://www.cubrid.org/cluster. CUBRID Cluster is an open source clustered DBMS for high scalability including global schema, distributed partition and load balancing features. It is a spin-off project from CUBRID project and supported by NHN.
Sequoia is a database clustering middleware offering load balancing and transparent failover. Databases are replicated over multiple nodes and Sequoia balances the queries between them. Sequoia supports online maintenance and recovery operations.
Eddie acts as a high availability WAN and LAN clustering tool for web servers (including Apache). It provides load balancing at two levels (DNS and LAN), failover redundancy, and admission control to maintain quality of service levels.