I've searched high and low for freeware or open source RAM drive programs, but in general all the free one were either very incomplete and required heavy manual editing/compiling of files, extensive use of the command line, or had arbitrary limits on drive size that made them useless.
I was willing to pay for a full featured program, but many of these had arbitrary OS restrictions, and since I'm using server OS, I would have had to spend hundreds or thousands of dollars to get something like SuperSpeed's RamDisk 11. I was about to purchase Dataram's RAMDisk (and it does have compelling features for the price), when I stumbled upon ImDisk
ImDisk is a virtual disk driver with the ability to create and copy images to system memory. It has a signed 64-bit driver and no practical limit on disk size. It's easy to install (a bit harder to remove) and extremely lightweight.
I've been using ImDisk and a variety of images I've created to really put to use the 24GiB of RAM I've got in my primary system. I have images for my games, which all but eliminates streaming pauses and significantly reduces load times. I run my smaller virtual machines from RAM disk images, making response virtually instantaneous. Basically, anything that is disk limited that I can fit into about 20-22GiB I can vastly speed up by dumping into a RAM drive.
Disks can be created and mounted on the fly, and formated as you would any other disk. You can back them up to image files and mount them later, with their contents intact.
The biggest downside is that you have to do everything manually. The program is not hard to use, but it's not automated in any way. Still, for the price of zero, I'm pretty damn impressed.
This is the interface:
And here is a bench of the disk I put Crysis on:
As you can see it's more than an order of magnitude faster than good SSD; access times are also in the nanoseconds.