Is there any type of working visa for Americans visiting Canada?

It very much depends on your age and or skills.

There are programs for people between the ages of 18-30 that would allow a one time visa (may be repeated for US) for up to a year to be issued in a special program. It would provide an open work permit, but you must be a full-time enrolled student.

You could look at the provincial nominee programs for Nova Scotia or New Brunswick to see if you meet criteria that they are looking for and then follow their process. If you meet them then as a US citizen you would take all of your documentation with you to a Port of Entry and may apply at that place for a work permit.

Not that you can apply for. IF you have the proper qualifications to be eligible for an employment visa, and IF you can find a qualified employer willing & able to apply for an employment visa for you, you might be able to work in Canada. Before employer can consider any foreign applicant, they must first prove there are no Canadians qualified & available for the job. If you see job ads stating "must be authorized to work. . . " then the employer cannot and/or will not obtain any employment visa - not qualified to consider foreign applicants, only citizens or legal permanent residents (PR).

Note that legal permanent residents (no need for costly employment visa!) started complaining by the end of 2011 that after a year in Canada with intensive job search, despite their degrees & experience, they cannot find any kind of job at all! Immigration rates have been too high too long & it is catching up to them.

Details on the Immigration Canada website. Look up the special TN visa as well to see whether you could ever qualify for that.