I shoot all my pictures in Olympus RAW format, and do most of my conversion and most of my editing with LightZone for Linux. Occasionally though, I may have several dozen photos that I want to treat like snapshots and just make quick JPEG images from them.
The Olympus RAW format hasn't been too compatible with most of the open-source Linux tools. The standard dcraw utility gave less than stellar results, leaving exposure and color slightly off and hard to fix. I did install ufraw and gnome-raw-thumbnailer so I could get nice thumbnail images in Gnome of my raw images.
For those images I want to do a quick and dirty bulk conversion to JPEG, ufraw-batch is the right tool for the job. From a command line, while in the directory with your images simply do:
ufraw-batch *.ORF --out-type=jpegAll of your raw images in the directory will be converted to a high quality jpeg image. There's additional options that can be added, but I found it sufficient for snapshots. And, you still have the RAW image if you ever want to clean up that one shot and print a poster!