There was a great design concept I saw a couple of years ago. A winged craft, looking very much like the old British Vulcan bomber, that had turbojet engines and one off-the-shelf russian rocket engine.
The concept was to take off with LOX and a bit of JP4 for the turbojets. Hit a tanker and top off with JP4 (kerosene), light the rocket and fly a sub-orbital mission around 60 miles high and mach 10.
For safety, you could build a "crew escape module", like the FB-111 has.
At the apogee, it opens hatches in the top of the vehicle, and kicks out an upper stage that goes on into orbit. That's the only "throw away" part of it.
Granted, you still need a bit of heavy lift for major components of big projects (man rating not necessary). But this thing you could fly litterally every day, boosting components and supplies for bigger missions.
But it would obviously also be able to be copied, or bought outright, by folks like the Saudi's, or whomever. Or even some private individuals. And THEN where would NASA be? Out of a job? Can't have that.