Caching expensive content

A friend of mine asked me for some suggestions for tools that allow caching content that was generated through some expensive process. I’ve had good success with OSCache but offered him this list of open source projects to check out:

• SwarmCache (cluster-aware caching)
• OSCache
• EHCache (used in Spring, too)
• JBossCache
• JCS (Java Caching System)
• WhirlyCache

Also look at at Cache Providers, it summarize some of the differences between these cache providers.