A few months ago Apple started shipping a new type of hard drive in their desktop Macs that promises the blistering speed of a Solid State Drive (SSD) with the large capacity of a normal, rotating hard drive (HDD). Essentially what they have done is to glue an SSD together with an HDD into what they call a Fusion Drive using a management system called CoreStorage (which now also lets you encrypt your whole HDD). The user only sees the usual single HDD in the upper right of their desktop, but the system is constantly monitoring which files and applications are being used, and then moves them to the SSD for very fast access. However, for those very large movies, iPhoto and iTunes Libraries, the system keeps them on the much slower HDD thereby giving the user a large and very fast drive. The reviews are starting to come in and for the average user, Fusion Drives seem like a good merging of the technologies. Currently the only machines that come with the Fusion Drive option are the new iMacs and Mac Minis, but it is possible to build your own fusion drive in an older desktop, and if you’re willing to pull out the DVD drive, you can even do this with a laptop. However, you might still need your DVD drive on occasion, so turn it into an external DVD drive.
Edit: I’ve just completed the first step of this with my laptop, the chassis above and a 240GB 6Gbps SSD. I transferred the existing HDD to the new chassis and put the SSD into the original HDD bay. I am having to manage the data on my own, but I now have a very fast boot drive and the large VM’s and libraries are stored on the much slower, but bigger HDD. As an added benefit, I recently learned that TimeMachine is able to back up to multiple locations on a rotating schedule so I now have my external backup and a new internal backup of the SSD.