I'm quite a fan of using DOIs to refer to online resources when possible. However, some DOIs are a bit ungainly, and particularly for readers working from a printed bibliography, they're outright inconvenient. Who wants to type in something like
10.1002/(SICI)1097-0258(19980815/30)17:15/16<1661::AID-SIM968>3.0.CO;2-2? Even when working from a digital copy, a string that long is bound to get mangled somewhere if it gets copied and pasted around, sent in emails, etc. You could use a conventional URL-shortening service, but that's probably not appropriate in the context of a published paper. So, how can you continue to get the benefits of the DOI system without exposing your readers to long, ugly URLs?
The answer is the shortDOI service, which transforms DOIs into shortcuts that are a lot easier for your readers to use. Every shortDOI generated is itself a DOI, so the conventional risk of a URL-shortener shutting down and taking the shortcuts along with it isn't a problem. As long as the DOI system is functioning, shortDOIs will be resolvable.
For example, the DOI
10.1109/JRPROC.1929.221679 can be dereferenced by using the URL
http://dx.doi.org/10.1109/JRPROC.1929.221679. When this is shortened with shortDOI, the result is the DOI
10/bpc. This can be dereferenced with the URL
http://dx.doi.org/10/bpc (note that that's no different than any other DOI), but, more importantly, it can also be dereferenced with the URL
http://doi.org/bpc. It's this last URL that is important for our purposes, as it's the shortest.
Now, shortDOIs can be manually generated, but why bother, if the process can be automated? I use BibDesk for managing references, and BibDesk is a scriptable application, so an AppleScript was the easiest solution to the problem. I've posted the script on GitHub; you can find it here. For every publication in a BibDesk document which has a DOI entered and which does not have a shortDOI shortcut, it will retrieve the shortDOI shortcut for the publication's DOI, and store it in the URL field.