When I am in a code or design rut, I tend to find a non-dev coworker to discuss the problem with. It forces me to explain the problem in great detail and I'll usually find something I missed in the process.
What are your "unsticking" methods?
Some of my tactics:
I imagine the person in my life who could best help me solve the problem, and assuming they aren't available on short notice to help me, go find a place where I can be alone, and explain the problem out loud as if I'm talking to that person. Eventually, in the course of trying to convince them that I /really/ have a problem, I usually come to the same advice that they would have given me.
I try to have two or three decently sized tasks before me at all times, so if I get stuck on one, I can take a break and work on the other. This allows me to be productive towards some goal, even if it isn't my primary task at the time. However, if I hit a wall really hard, sometimes I just need to walk away - take 15 minutes, grab a cup of coffee or a soda, take a walk, etc.
Keeping some good music (slow volume) so you keep in the mood.
When you feel that you are not able to concentrate on whatever you are doing. Trying to move your legs or tap them or bounce them for a while that will make your blood flow wild again. The reason for you becoming disturbed is the reason so some tensions or lack of blood flow in body as the body is staying in a same position for a time. Try to circulate your blood better and u get your job done.
Try to talk to someone about what you are doing (someone close to you, in my case my fiance). Its not important if the other person understand it or not but get a good feel for sure.
If you get stucked get your pen paper and get the thing visualized with some boxes, names, arrows etc try to understand the flow. Rethink over it.
Get something to eat and just sit and eat for a while an idea might struck you :P.
Get a screwdriver and open you machine or laptop or notebook and try to find out what wrong with it...??? why its not giving me expected result :P (kidding)
The one that i personally do most of the time when i get stuck, funny though - get a mirror start looking on to it. Make faces, talk to myself, start wondering keeping it in front of me. keep staring at myself. That help me out to get fresh again and increase my power again. Wierd eh....but works for me.
If you are working at home, you can go do jogging outside or take a walk. It's good for your health and it helps to think about the problem on which you are stuck on. If find this to be effective, because it helps me get a better overview of the problem. Sometimes your just focusing on the wrong part of the problem and when you get a better overview of the problem, the solution is easier to find.
Just as another tool, you could get a set of the Oblique Strategies cards.
Oblique Strategies [...] is a set of published cards created by Brian Eno and Peter Schmidt first published in 1975, and now in its fifth edition. Each card contains a phrase or cryptic remark which can be used to break a deadlock or dilemma situation. Some are specific to music composition; others are more general.
The authors are/were musicians that used the cards to foster creative thinking.
You pick a random card and get a 'dilema' statement. For example:
"Remove specifics and convert to ambiguities"
Although some times they are just nonsense if you are not trying to compose music, the simple exercise of trying to understand what the card suggest might help you unlock your mind from your current thoughts and help you think from an unrelated, unexplored path.
There are some downloadable versions, and also a couple of web sites where you can read them online. I'm pretty sure you can get them also as an iPhone or Android app, but I haven't looked for them. I have them as a Mac OS X Dashboard Widget called 'Oblique', but I just searched for the link and it seems it is not online anymore.