Task services, which let you post odd jobs online for would-be gofers to bid on, have become popular with individuals looking to shorten their to-do lists. On a recent business trip to San Francisco, I tested two of them to see how they might help a business owner stay more productive on the road. TaskRabbit has had an "office help" category since launching in 2008. Zaarly.com, a Craigslist-style goods and services marketplace, has served business folks since its launch last May.

When I got to town on Tuesday, I posted two jobs on TaskRabbit: transcribing an interview and taking my clothes to the dry cleaner. TaskRabbit can assign jobs automatically to the first bidder who meets your maximum price (which the bidder can't see), or you can choose to see every offer, as I did. Within 10 minutes, I had about half a dozen bids for each job. After checking online profiles—including pictures, ratings, and LinkedIn pages—and chatting with my top choices on the messaging system, I picked two TaskRabbit veterans willing to do my jobs for about $30 each.

Lauren, an office admin, met me at my hotel, took my pants to the dry cleaner, and returned them promptly the next day. She was courteous, if slightly hurried. Jenn, a receptionist by day, picked up my interview recordings and e-mailed me a perfectly transcribed Word document the same night.

I also posted two jobs on Zaarly.com: delivering two packages from my hotel to a meeting and buying me a dress shirt. I typed in a description of the work and my asking price, which users on Zaarly can view. Unlike TaskRabbit, Zaarly offers little information on its workers: no links, no pictures. After weeding out several fishy offers for the delivery job, I chose someone to do my delivery for my $20 asking price—less than local courier services. After some haggling, another worker agreed to buy and deliver a shirt for $100 but warned that at that price, I'd have to settle for one from an outlet store.

Though my delivery guy came through, his scraggly hair and long overcoat turned some heads. And my new dress shirt was too small and had metal buttons and a trendy gray collar; I'd wanted a simple light blue button-down.

I had one last task: doing an expense report. I posted the job on both services, but the offers that came in were all too high—about $100 to scan receipts and type the amounts into Excel. To prove the task was not worth that much, I did it myself in about 15 minutes in the hotel lobby.

My overall experience with these services was good. I liked delegating these mundane tasks, and I could see hiring these workers for all-day jobs like organizing a supply closet. Though job offers came in faster on Zaarly, ultimately I found TaskRabbit to be the more mature and professional service. Call me old school, but I like knowing a little more about my assistants.