Old'aVista is a search engine focused on personal websites that used to be hosted on services like Geocities, Angelfire, AOL, Xoom and so on.
The search functionality of FrogFind is basically a custom wrapper for DuckDuckGo search, converting the results to extremely basic HTML that old browsers can read.
The Old Net is an attempt to restore vintage web browsing on vintage computers. It uses the Internet Archive: Wayback Machine API and a proxy that strips out any incompatible javascript and stitches together as many links as it can.