I used Haul Bikes (haulbikes.com) this year on a bike I acquired and a buyer used them last year on a bike bought from me. Both instances were outstanding, professional and decent value (not cheap). The only downside, and It was not a negative factor for me, is that the process can take a couple of weeks since they consolidate shipments for their own efficiency. I would not hesitate to use them again.
I also used uShip (uship.com) several years ago with very satisfactory results. The thing to realize about uShip is that the web site really just acts as a brokering site for buyers and shippers to meet and come to terms. As mentioned above, you need to carefully evaluate the ratings and customer satisfaction for each shipper who bids on your job. Choose carefully. I would use the service again with the caveats mentioned.
