The more hybrid archives we work with, the more obvious it becomes that we need access to repositories of older software (or 'abandonware'). For older formats you often find that not only is the creating software obsolete, but any migration tool you can dig up is pretty out-of-date too. Recently I used oldversion.com to source older versions of CompuServe and Eudora to transform an old CompuServe account to mbox format with CS2Eudora. The oldversion site is really valuable and we could use more like it, and more in it. The trouble is, collecting and publishing proprietary 'abandonware' seems to be a bit of a grey area.
In 2003, the Internet Archive obtained some exemptions from the Digital Millennium Copyright Act (DCMA) that has allowed them to archive software, but this has to be done privately with the software being made available after copyright expiry. Not much help now, but promising for the long-term. The best thing that could happen (from an archivist's point of view) is that individuals and companies formally rescinded their interests in older software and put them in the public domain. Ideally they would put an expiry date into the initial licence before the software becomes abandonware.
I'm curious to hear about other good abandonware sites, especially ones that include 'productivity software' (our focus is here rather than gaming!). The Macintosh Garden is a good one, and Apple themselves also provide access to some older software, like ClarisWorks. What else is out there that we should know about?