Good alternative is nURL Suffix Rated 4 out of 5 stars

dotComplete is dead. Use the URL Dot. https://addons.mozilla.org/cs/firefox/addon/13299

An alternative to dotCOMplete that works on FF 3.5 (need to force the compatibility though). Nice work. (thanks IdoMcFly)
https://addons.mozilla.org/en-US/firefox/addon/9201/