Sorry for the COASTAL delay in responding about the ramps. I've finally come back to the forum after a long while.
As for Keyport...
the town finally got their Green Acres/NJDEP/Wetlands/etc...permits together and construction is underway to re-do the American Legion Drive. They have already finished from the Ye Cottage rampward to the charter boat dock. It's been about three weeks since I was there, so they very well could be working down near the ramp by now.
As for other places...
there is a spot in South Amboy. Follow John St. to Rosewell make a Right on Rosewell. Take the road split to the left (the baseball fields will be on your right). Make a quick left into the gravel yard and follow down to water. This puts you on the Raritan Bay right where the River dumps into the Bay; i.e., east of the Driscoll.
There is also a spot in Sayerville. West of the Driscoll. From Main Street (Middlesex County Rt. 670) take River Road due north to the Raritan River. They charge to launch. I think it was like $15-$20 last season.
I'm talkin bout the Lifestyle of the not so rich and famous.