I am sure you have read about beanstalks, spacetethers and space elevators. With the emergence of strong nanotubes these concepts are seriously studied again, but still the sheer immense size of those projects (cable lengths up to 100.000 km) is very challenging. Something less ambitious would be to get some kind of beanstalk to LEO (from there cargo can be tethered by tranportships that remain in space). picture this: - a statospheric blimp at 50 km altitude - some kind of beanstalk on top of it of say 150 km Obiously, you cannot use a large wooden/steel pole or something , would be really heavy and the corriolis forces will bend / break the pole etc etc. What i propose is a light flexible tube/straw with really thin walls made of kevlar. Suspended on the blimp there are aircompressers that scoop air and pump it under high pressure into the tube. at the top of the tube there are a few nozzles to point sideways and downward/ The high pressured air serve 3 purposes - give stiffness to the tube, so it can be used by a climber - stationkeeping (the sideway nozzles) - keeping the tube erected (downward thrust nozzles) You can imagine that a tube that consists mainly of compressed air is lighter than made of most solid materials... The airpressure should be able to keep the tube erected and steady and allow for some object to be lifted, but we cannot expect something really heave, like a complete spacestation module climbing one tube. Proposed therefore mutiple tubes arranged in triangle / square or circular fasion and spread the load of the elevator platform evenly.
Note that blowpipe of 150 km does not have extreme pulling forces that other space tethers have, in fact most are pushing forces, of the weight of the blowpipe resting on the blimp. I introduced Kevlar merely to withstand the high airpressure within the tube, but maybe we can get away with even cheaper pressure resistant material than Kevlar.... Also, if you combine the blowpipe tower with the MXE tether concept (as discussed overhere) http://www1.msfc.nasa.gov/NEWSROOM/background/facts/momentum.pdf one could opt for the blowpipe to be just 50 kms long provided the skyhook that picks up your cargo has a long tether and a really elliptic orbit to make a narrow earth passage. This would further lower the cost for the materials used and makes the specifications even more feasible (less airpressure needed to keep the blowpipe erect). This means however that the earths atmosphere will impose some drag on the skyhooks tether, but you could use the blowpipe and the tether to transfer electricity from the blimp to the towing satellite. In turn it could use this electricity to electrodynamically reboost its orbit. In fact this means that towing satellites DO NOT NEED solarpanels at all!!! They just power up while they pick up some cargo... the blimp can be moved while the pickup is done, giving a larger timeframe and more flexibillity for the pickup and the powerup to complete.
