Is haste useable in combination with unarmed attacks?

Question

As a monk most often uses unarmed attacks I'm wondering if the haste spell (talking about natural weapons or manufactored only there) can provide an additional attack for them?

Answer 1

Creative director James Jacobs in a 2011 Paizo messageboard post says that the feat "[R]apid [S]hot and flurry of blows both stack with haste" (links added). Such effects are, presumably, not haste effects, so the effects of all three are cumulative, making, for example, the monk possessing the archetype zen archer very pleased.

The spell haste allows an affected creature to "make one extra attack with one natural or manufactured weapon." But,—although perhaps neither a natural weapon ("Some creatures do not have natural attacks[; t]hese creatures can make unarmed strikes just like humans do," says the Universal Monster Rules on Natural Attacks) nor a manufactured weapon,—a "monk's unarmed strike is treated as both a manufactured weapon and a natural weapon for the purpose of spells and effects that enhance or improve either manufactured weapons or natural weapons," making the monk's unarmed strike specifically haste-friendly even while, by a strict reading, a typical creature's unarmed strike may not be.

Note: This GM does not support forbidding a nonmonk using unarmed strikes from gaining the extra attack benefit of the haste spell because of the spell's weird specificity and the unarmed strike's unique classification. Dude wants to punch dragons? He'll need haste and a lot more besides! Also, using a natural weapon like a bite or tentacle—instead of an unarmed strike—during a flurry of blows is better addressed in a separate question.