Getting started woodworking- what can I build with these motors?

[C-Bag]

Wow, lucky you! For what it's worth(and you are getting it free) I don't see hp as the limitation if you build or modify SAFELY. Good frames with proper guards all done right will mean you'll have quality equipment. Most manufacturers make their equipment as "economically" as possible. Smaller motors are cheaper. These are quality industrial motors that are made for harsh environments which means they are perfect for a dusty environment like a wood shop. Speaking of which. One of the first things I'd make or modify would be a dust collector. Not only is it a mess and a fire hazard it's horrible for your lungs.

Where I see your challenges will be in mounting and speed. Flange mount is not seen as much in the home shop equipment and not everything runs at 3400rpm, so you'll have to check your speeds.