Bit.ly is the perfect example, but there are lots of vanity URLs around too. They help promote your brand or website (for example, abc.de/website), or a cause (dona.te/help). And since they are shortened, users are less likely to fuss over typing. I mean, it's easier typing a short URL rather than url.com/ineedhelptoday, right?
What about you? Have you implemented custom link shortener?