A recent thread about air compressors for the shop reminds me of a solution that worked for me. I had a cheap 5hp compressor with 60 gallon tank located by my breaker box in an adjoining garage area. Air was piped to the shop via a 3/8" flex line and then distributed to 3-4 locations in the shop. As was posted by others, that's not enough air to run a good linear or ROS, but plenty for most other uses.
While nothing will bump up the volume from the compressor, it was irritating to not be able to break lugs or big bolts loose using my biggest air wrench in the garage. Rather than snake in a 1/2" air line to handle the big wrench, I hit on a great solution I'll share with you.
Simply get one of the 5-gallon "carry anywhere" air tanks sold at most auto parts stores, Sears or other places. The tanks are intended to be filled with compressed air and then taken to the site of the flat tire, or where needed without lugging around a compressor.
In my case, I removed and tossed the 1/4" line that came with the tank, drilled and fitted in a 1/2" air hose connection and put on a 4' long 1/2" air line. The tank filler was replaced with a 3/8" quick connect fitting to match the nearby 3/8" line in the garage.
The tank acted like a capacitor, storing compressed air and being able to release it in a burst equal to what you'd have with a 1/2" line. It wouldn't last long, but would be plenty to run the big hammer wrench at full power to loosen the stuck big stuff. Most of the time it wasn't needed and I could just use the little stuff to do normal air wrenching. However, when I needed a big boost, I'd just get out the tank, hook it inline where I was working and get out the big wrench.