I would like to see the Ebay of local grocery delivery. Maybe with three components: Buyers, Sellers, and Delivery people (for stores that don't already deliver). Matching people in the local area. Rating delivery guys and automatically choosing based on these ratings. Heck, it doesn't even have to have hands on involvement of the store in question - maybe the delivery guy himself can post a list of items he'll buy for you at the store.

Sure, you can use a large supermarket, but I'd really love to go online, see my local store(s), and click to purchase a handful of items and have them delivered within the hour as conveniently as a pizza.

It's one of the many ideas I'd build if I weren't already building stuff ;)