The folks at United MileagePlus have a new initiative the MileagePlus Small Business Network. It's targeting Small Businesses Owners to incentive them to run parts of their shopping through MileagePlus Shopping Mall. So far the mall targeted consumers only in their positioning.
To receive the bonus offer you have to enroll and run a transaction that gives you at least 100 miles into your account. An easy way to achieve that would be to move an upcoming Hertz/ Avis car rental to your account (75 miles/day).
Adding additional rewards to your standardized purchases is something every small business should do. I'm not sure why this hasn't been a marketing target before. Take advantage of this offer if you can.