There is no other substitute for fresh air and sunshine.  The enabler it becomes to allow your brain to race ahead and work on problems is amazing.  Why don’t many (any?) companies encourage a trip outside and/or sponsor an opportunity for workers to get away from the office once in awhile?  I think it really should be an option.  You know, once or twice a week a person should be able to get out to their favorite place with a laptop and wireless data and just work.  Turn on some tunes or just listen to the sounds around you – I guarantee that you’ll see an improvement in your world view, and help find an answer to that issue you’re working on.