CiWiki is very compact and doesn't require Mysql, php, Apache... 
It is ideal if you wish running a small wiki on a usb flash drive.

To run CiWiki from your usb drive, a few MBytes of free space are required.
1 - Copy the folder ciwiki-2.x.x on your flash drive. 
2 - Compile the code ./configure and make
3 - Start CiWiki with this command:
/media/disk/ciwiki-2.x.x/src/ciwiki -h "/media/disk/mywikispace/"

Another possibility:
 if you just want to store the wikipage on the flash drive, install ciwiki 
normaly and start CiWiki with this command:
ciwiki -h "/media/disk/mywikispace/"


Note:
The page will be stored in the folder /mywikispace of your flash drive.
/media/disk is the path of a usb flash drive for Ubuntu.
