Kitkat a work timer Bash script I quickly put together this evening out of interest, while I was waiting for some files to convert. I doesn't have any snazzy interfaces, or anything. This is just a quick n' dirty script. By default it uses 10 seconds of work time, and then a 5 second break, so you'll prolly want to edit the time variables to meet your needs. Time is measured in seconds.
Basically the way it works is, you launch the script manually (I'd suggest running it in the background), and then it runs in a loop until you tell it to stop. Within the loop there are 2 prompts. The first prompt tells you to take a break. The second prompt tells you to get back to work.
Read the code comments for more information.