I just needed to send faxes related to payroll taxes a few days ago, and ended up with another pay-as-you-go type service. Wish I'd seen this first. Since it's been three or four years since I've previously needed to send faxes, I'm unlikely to become a regular Fax Robot user, but the price is right (I'm paying .11 per page) and the simplicity of the thing looks great. Minimal hassle, no monthly fee, etc. were among my qualifications when I made a decision about which service to use.

Historically I used MaxEmail which was always fine, and a good deal if you need incoming faxes, but since I didn't need that and canceled my account with them a few years back, it was unnecessarily expensive.