A very simple thing you can clip a PCB into and keep it safe from accidental shorts or mount onto a more permanent fixture.
Inspired by things 24096 (the Raspberry Pi plate) and 32201 (XClip for Raspberry Pi) this one is a bit more applicable for lower resolution (0.3mm or higher) prints and far more functional than aesthetic.
It also has the benefit of being parametric.
Full details about this thing are available at http://thegaragelab.com/posts/parametric-pcb-holder.html - here is a summary:
I've provided the original source for the thing as an OpenSCAD file, it's pretty well documented so you can go ahead and modify it to suit your needs. The important parameters are at the top of the file.
I've also provided STL files for some different board layouts including the Raspberry Pi Model B, the Gumstix Tobi and the Gumstix Chestnut43 (the variables for these are supplied in the OpenSCAD file as comments if you want to use them for yourself).
To use - do the following:
1/ Download (or generate from the OpenSCAD source) a STL file matching your board.
2/ Print it out.
3/ Unfortunately this is not 'plug and play'. If your slicer generates support material there will be some in the slots, if it didn't then the top of the slots will have sagged a little. Use a knife, file or other implement to clear them out.
4/ Insert your board. If the base plate is not flexible enough to allow this you might want to change the BASE_PLATE_HEIGHT variable in the OpenSCAD file. If the tops of the mounts snap off while you try and insert the board you may want to increase the MOUNT_SIZE and/or MOUNT_EXTRA variables (if only one snaps off it's not too bad, I'm using a couple where that has happened and it doesn't really matter).
5/ If you have added mount points (screw/bolt holes etc) you should remove the board, mount the holder and then insert the board again.
That should do it. I find these very useful at work and in my home lab where I have a lot of prototype boards in use. It keeps them safe from shorting out and lets me bolt a few to a single base while we are still in prototype stage.
If you have settings for more common boards (Arduino variants for example) I'd appreciate it if you left them in the comments for others (including myself) to use.
UPDATE: I've modified the default values in the AutoSCAD file to produce more resiliant versions of the frames (see 'pcb_holder_v2.scad'). After using these frames for a while now on a number of different boards it became evident that it was very easy to snap off the top of the clips - this is now resolved so you can insert and remove boards with low risk of damaging the frame. I have NOT updated the STL files attached to this thing yet, so the best bet is to grab the OpenSCAD file and generate your own STL's as needed.