as a wayback machine user (from wayback), let me give you a quick summary:
Before the Alexa Web site crawled the internet looking for updates to pages, it made use of users using the Alexa Toolbar. This is an add-on to the Internet browser that would alert Alexa (and the archive) to pages on the Internet, as well as updates to those pages. The archive.org would then cache these in to what you see now.
Here’s the subtext: people who had their pages visited often by users with the Alexa Toolbar will be represented, and those that weren’t as visited will be not be so much. If you have several entries, then assume that you were either popular, updated often, or had a serious internet stalker who loaded ancient Internet spyware.