I had some awesome success with using Onsite POS add-on to Netsuite.   Check out a recent article here....

http://www.pcworld.com/businesscenter/article/159349/netsuite_unveils_new_suite_for_retailers.html

Had over 2700 customers through our warehouse in 2 days.  1300 register rings and 22,000 items sold!

Check out this video to watch the madness. 

http://www.vimeo.com/2511863