I couldn't be happier than this: I found a site that archived almost all the Opera versions, the 16 bit versions, as well Here it is for you all: [url=http://browsers.evolt.org/]evolt.org Browser Archive[/url] newscpq
What's wrong with official archive at http://arc.opera.com/pub/opera/ ?
Thanks! That's interesting!
In case you're not familiar with it, here's Opera's own archive with Windows versions back to v3.21 (English back to 16-bit v3.62). It looks like evolt.org has a few 16-bit and 32-bit versions even earlier than that.
(Edit: oops! sgunhouse beat me to it)
www.oldapps.com has a decent selection too.