.pk is the top level domain of Pakistan. Most Pakistani website owners uses .pk domains for their websites. The .pk domains are not too expensive and will be suitable for your small business or a website.
In year 2007, second level domains  also becomes available for website owners such as:
*).pk
*).edu.pk(for educational institutes)
*).net.pk
*).gov.pk(only for Government of Pakistan)
*).web.pk(for websites)

Lower Level Domains are not  granted to any one yet.