I have been using Google ever since it became a public project at Stanford and the same is true of Yahoo. However, there are a few tools that I use for historical analysis and internet archeology.
Before Google, I used AltaVista a lot because it had the greatest coverage of the internet. AltaVista was a project at Digital, or DEC as it was known prior to merging with Compaq and then HP, as more or less a demonstration of the scalability of their equipment and covering all of the Internet. This means that they have a wealth of information back to 1994 or earlier.
Try using the date features in the Advanced Search and setting the date ranges to ranges such as Jan 1, 1995 to Dec 31, 1995. As an exercise, look for the following. When was the term "Enterprise Content Management" first used? When did it become popular and by whom? When was the the term "Customer Relationship Management" first used and by whom?
I also use Alexa and the Wayback Machine for historical views of web sites. Alexa made regular copies of the internet on a huge disk machine allowing you to see what a web site looked like on a particular day and also giving statistics on the usage of those pages. That view is now provided through the Wayback Machine. Alexa and Alexaholic are interesting tools as well, but do not go very far back.
What tools have you found useful?