A chain on top of the cubicle
I believe in the LEAN methodology, Toyota follows the same methodology in the company. In Toyota, if a guy faces a problem, he has a chain - to pull - right above his work-area...when he pulls the chain, his manager sprints to him (literally, his manager runs to him) and tries to solve the problem in 60-90 seconds. If he can't figure the problem in that time, the whole supply line stops. Although, this sounds crazy, but Toyota doesn't want to take anything forward with a quality glitch.
After this, I definitely think that we all need an expert at workplace who can solve our problems in 90 seconds (like the guy in Toyota). This is why, a seasoned resource of your team needs to understand that he needs to mentor/help his colleagues for around 30% of his time, and work only for the rest 70% of his time. Also, nobody likes to email a problem, unless that's the only option.
How convenient it would be for a rookie (in a team) if he is provided with a chain on top of his cubicle, and when he pulls the chain, his lead/manager sprint towards him to help him out. Don't laugh :-D.