Well i got a decent electric air compressor (30 amp) for xmas and i would like to hook it up just under my toolbox. I want future capacity for lights or something else back there. I do not want to hard wire it, i'd rather keep it inside when it's not needed, some kind of 30 amp plug would be great... it needs to be weatherproof though..

what can i use?

 

Are you sure it is 30 A DC ?
That is along the lines of a winch power requirements.

For a 30 A DC plug, you are going to have to use the same connector as the winches use. Think that makes the wire size 6 or 8 AWG ( not 100% sure on that ).

 

That winch/jumper connector is overkill for 30A. A standard Bosch/ISO relay can handle that much, and it uses common flat blade terminals.

12V connectors don't have to be weatherproof to work, but if you want them to last, use this:

 

That is true.

The cigar lighter is 20 A fused, so 16 A load ( using 80% rule ), I was having a hard time thinking of a 30A DC "connector" ( Cigar lighter, SAE plug, DC coax, etc ) and could not think of any aside from the winch style connector.

They do make that style connector, but for lower loads then a winch ( which now that I think of it, a winch is higher than 30 A ).
Same look, just smaller. A member posted them some time ago, I am still trying to find the URL to them. They were just the connector shells with the crimp terminals.

EDIT :

Think it was the Anderson Power Products Multipole product. The 30A is a single ( in red or black ).

The multi pin start at 50A ( which is over kill size wise, but will get the job done), in a single plug in style.
Have not found the accessories with the dust caps like the Warn connector.