Windows: Ever need an email address that you know is stored in one of your documents, but you have no idea which one? Easy Email Extractor is a freeware program that will go through any or all files or folders and pull out any email addresses it finds.
You can also use the program to extract email addresses from web sites, but since many sites avoid having actual email addresses in their HTML code to avoid spambots, you may not have a lot of use for that feature.
Nevertheless, as someone with well over a decade's worth of text files stored on my various computers, Easy Email Extractor ended up finding four email addresses I thought I had lost forever. Developer NoVirusThanks has a slew of similar small utilities available on its page as well as usually safe download pages like CNET Downloads.