There are a lot lists with software archives, but many ones are obsolete/outdated.
Do you know http://www.heise.de/software/
- unfortunately it's German (but most software is English anyway)
- many software marked as DOS has in fact no DOS version (seams the reported confused it with DOS-box on NT)
- but also many useful diagnose/benchmark software can be found there, links and versions are quite up to date
For example I found
- h2bech (harddisk benchmark tool) and
- fttest (monitor test tool)
And there are even more tools which could be potentially added. Are you interested?