One of the primary ways I use Google Reader as an archive is for backing up my Twitter stream. If you’ve ever tried to go back and find something you tweeted last year, you’ll realize it is a slow and painful process using the Twitter interface. However, by adding it to Google Reader you’ll be able to load and browse through your timeline much quicker since the data is actually stored by Google, not by Twitter.

You can tag, search, organize, and share past Tweets exactly the same way you can with all of your other items in Google Reader. This in itself is extremely powerful. For example, maybe you’ve recently conversed with a potential customer on Twitter and you’d like to keep your statements on record and easily accessible. Simple enough: tag those Tweets with something like “prospect.” Later in time if you wish to re-visit that conversation, just go to the “prospect” tag in Reader.

Keeping with the Twitter theme, you can also archive Twitter searches. If you recently participated in a Twitter-based chat around a specific hash-tag, simply grab the RSS link from a search query for that hash-tag on search.twitter.com and you’ll be able to read the details of that chat months down the road. Anything that is search-able can be archived by Reader, not just hash-tags. You can keep a backlog of results for any search query and just archive the RSS feed of the results.