Best Commercial Real Estate Property Search: Loop.net
They offer a free online search for commercial property searches for properties which are for sale and for lease.

ReMax Commercial Property
Remax offers a good line of commercial properties from their website remax.com. They also offer a search for commercial realtors by area.

Finding good resources for commercial properties online can be hit or miss right now. There are many websites out there that appear to offer commercial properties for sale or investment, that appear to be scams. Stick with the reputable sources such as the websites offerred above and you should be able to avoid many online scams.