I posted about TaskRabbit before, but I just used it for the first time tonight. They emailed me a coupon for a free task (up to $20; they send these out pretty frequently), and I posted a request for someone to pick us up some chicken wings and bbq from Hard Knox in the Richmond. Half an hour later, and a Rabbit was on the job. We ordered online from the restaurant, but you can also just have the runner pay for you, and reimburse them through the site.
If you haven't used it yet, try it out! Use this link to sign up and you get $10 off your first task (probably enough on its own for a grocery run, dry-cleaning pickup, or anything else in the 1/2 hour category).