If you tend to run out of memory before you run out of processing power, you might want to take a look at IBM's Active Memory Expansion feature built into POWER7 systems.
Active Memory Expansion is somewhat of an oxymoron -- it actually employs memory compression technology to compress in-memory data, IBM says, which ironically expands the memory capacity of POWER7 systems. Sounds cool -- and complicated. Still, IBM has several resources available to help you understand what it is, what it does, and how it might help your business.
If you're running AIX 6.1, you can use one of IBM's handy tools called amepat, which, when run against existing workloads on POWER6 systems, will give you some insight into the benefits you'll get by moving to POWER7. In addition, here's a key Active Memory Expansion page, along with two white papers authored by two different IBMers -- why not just one? Who knows, but for us, we find that sometimes reading information expressed in slightly different ways can help cement concepts better than reading one document multiple times: