I would highly recommend Garden Grocer, it's easy to use and they were very prompt with their service.
EXCELLENT JOB!! We placed our order online well before our planned trip to WDW (6+ months before). Due to an foreseen event we not only had to change our date of our trip and therefore our order date, but also had to change our resort. The transition was handled beautifully with very limited interaction on our part. In fact, we were waiting at WDW Express when we received the email that our groceries had been delivered to our resort. FANTASTIC!
Highly recommend - excellent service and quality - wished I knew about them sooner!