6. search for "monta~na" and find spanish sites about mountains, not english sites about Montana. Yay Yahoo for respecting accents!

Edit: Boo news.yc for NOT supporting unicode. Or HTML-entities, for that matter. Blub supports Unicode! http://www.joelonsoftware.com/articles/Unicode.html

Google can do #4

site:whatever.com <query>

Thanks for the linkdomain tip, it's quite good. linkdomain:http://www.paulgraham.com/

Yahoo has an API, which google no longer does. +1 for Yahoo.

linkdomain:mysite.com nice!