On American Express's Open Forum blog they posted "30 Ways To Boost Sales Without Discounting." Below are my favorite of those tips.
1. Future-use coupons
Use wording such as "For every $50 you spend tonight, you get $10 off your next purchase of $50 or more." Your customers have an incentive to spend at least $50, and you'll get an additional $50 in purchases when they apply their future-use coupon.
Have you trained your staff in the power of suggestion? Many restaurants do, but you might have overlooked it. Wait staff or counter staff should always have an upsell suggestion at the ready. "Would you like fries with that?" is only the beginning.
Offer free shipping or faster shipping for purchases made within a certain time or over a certain dollar amount.
14. Bulk order rewards
Customers who buy in bulk get a reward of some kind, such as a free customer club membership or a free T-shirt or other promotional item.
Highlight a particular item and put it front and center. Sales will increase just because it is "the featured item" even though it isn't discounted.
16. Customer reviews
Gather positive customer reviews and put them beside the product or service being offered. Testimonials are powerful.
30. Rewards and levels
Offer rewards, but tie them to dollar amounts or commitment levels. The greater purchase or commitment garners the greater reward.
You can view the complete list at: http://www.openforum.com/articles/30-ways-to-boost-sales-without-discounting