I've used HomeRuns (http://www.homeruns.com/) a few times and
have been quite happy with the results. They deliver in any
2-hour window you specify, and if you order more than $60 worth
of stuff there's no charge for delivery. ($10 otherwise.)
And you can set up online shopping lists to use as the basis
for future orders.
I think Homeruns serves the New England area only, but there are
at least a couple similar US-wide services. Their prices seem
comparable to the local monopoly; I haven't used it for produce
yet so quality hasn't been an issue, but I kind of assume they
won't bring you garbage because if they did you'd never use them
again.
I have mainly found it useful because I don't have a car, so I
use it to stock up on heavy stuff that I can store for months.
(canned soup, pasta sauce, soda.) They're missing a few specific
products that I like, so I still need to make regular trips
myself.
-- Gerald Oskoboiny <gerald@impressive.net> http://impressive.net/people/gerald/