My public service employer has a gift acceptance policy that I think applies to any situation where you do not want to create a perceived conflict of interest.
There is a 3 part test for non-monetary gifts (monetary gifts, including gift cards, we can't accept):
1. Social Standard – the gift is of a value deemed not excessive given prevailing business and social standards
2. Reciprocity – the gift is of a nature that one could and would reciprocate
3. Reputation - Accepting the gift would not jeopardize the reputation of the (Professor)
When I saw this I thought it would be a good idea for a colleague-type gift: http://www.bedbathandbeyond.ca/product.asp?sku=18156660&
Hope that helps!
