Simple way to collect the Sentinel data of a given ROI?

The latest release of ESA SNAP (6 beta) features so-called AOI monitoring.

http://step.esa.int/main/download/

It allows you to define a region of interest, schedule searching for the data and apply processing chains (as defined with the graph builder) on the data automatically. And with the new sci-hub integration you can download S1 data directly in SNAP (you enter the same user credentials as on https://scihub.copernicus.eu/).

However, I don't think that only downloading subsets works by now. The whole product is retrieved but as soon as you integrate the subset operator in your graph, only the desired area is proessed.