is there such a thing as a 2 prong surge protector?

According to howstuffworks.com the most common type of surge protectors contain a metal oxide varistor or a gas discharge arrestor that utilizes the grounding wire to divert extra current.

However, the neutral wire is usually also used in conjunction with the ground, but not full protection when bypassing the 3rd prong.

That said, it's never considered safe to use bypass the 3rd prong (even with 2 to 3 prong adapters) and it is likely your insurance / the manufactures insurance will not cover damages caused as a result of such use.

It wouldn't make sense--the third prong is used for the ground, which would allow the surge protector to get rid of a power surge.