Sometimes, when working with a LAMP application I miss a nice little thing called connection pooling. Recently, a colleague sent me a link to SQLRelay by firstworks.
It looks to be a very flexible and very usable piece of software. It supports a wide variety of DB back-ends and clients.
One of the parts I'm interested in at the moment is the load balancing and failover capabilities. I'm working on getting a good test environment built so that I can actually put this thing through it's paces. I'll likely be using EC2/S3 to do that so more on that adventure later.