Remote geoprocessing solutions?

Take a look on pyWPS, an OGC Web Processing Service implementation. Its easy to install on a python environment. Most of the examples use GRASS GIS as pyWPS only implements the interface for remote handling, but it is possible to use any GIS backend to do the actual processing work.

So check out the gallery first, to get an idea what is possible and feasible.

It is probably some quite large datasets you have to handle, and therefore i would perhaps not suggest a WPS solution, since you would be transferring data with the process request.

WPS 1.0 has limited capabilites for asyc. requests - which will be enhanced in version 2.0 - making the solution with WPS a little more feasible i guess - but for now and in general i think that the streaming of data through the process is going to be a larger bottleneck for you, than doing it on your I5...

It would still be possible to use a VPS server for processing (i do that myself) and have FTP access to my working directory - that works fine for me.