I have seen an increasing number of tweets questioning whether or not a popular link shortener — bit.ly — may be collateral damage of the unrest in Libya, particularly if Col. Gaddafi hits the Internet “kill switch.”
Further reading indicates that bit.ly is less vulnerable to being blacked out because of Bit.ly’s redundant name servers spread around the world. Bit.ly’s CEO responded to a Quora question with this.
So, I guess that answers that! And we probably don’t have to worry about dead links because of our widespread use of that particular URL shortener.
The domain hack generally (but not always) uses the ccTLD (country-code Top-Level Domain) to construct the desired URL. (The list of ccTLD’s is here.)
There are some other clever domain hacks out there. See some here.