Here is a very timely paper for many of the readers of this blog: Tax Planning of a Visiting Professorship, by Myron Hulen (College of Business, Colorado State University) & William Kenny (School of Business Administration, Portland State University). Here is the abstract:

A sabbatical leave and a visiting position at another university offers professors many professional and financial advantages. Among the financial advantages are often favorable taxation of the expenses incurred and income earned at the expenses earned at the visiting university. This paper discusses the tax implications of a visiting position including the rules of eligibility for traveling deductions, rules for deducting travel and transportation expenses, implications of taking a position outside of the United States, the problems caused by the Alternative Minimum Tax and other related issues. Also covered are the recorded keeping requirements and the use of the federal per diem allowances.

(Thanks to Anand Desai for the tip.)