Visas and Regulations
Let's start with the basics, many people transit through Qatar on their way to other destinations, if you are holding a valid onward ticket that departs in 8 hours or less you do not need a visa. However, you will not be permitted to leave the airport.
The only other people that do not require a visa for entry into Qatar are valid passport holding citizens of a GCC countries.
Now that's out of the way let's move on to everyone else, if you hold a valid passport from any of the following countries you may obtain a 30 day visa on arrival.
Andorra, Australia, Austria, Belgium, Brunei, Canada, Denmark, Finland, France, Germany, Greece, Hong Kong, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, Malaysia, Monaco, Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, South Korea, Spain, Sweden, Switzerland, UK, USA or Vatican City.
The visa costs QR 105.00 (US$ 28) and payment is credit card only, this tourist visa may be extended for up to 3 months. If you overstay the visa there is a $55 per day fine that must be paid by credit card upon departure from Doha International Airport.
If your country is not on the list above, then you will require a letter of invitation from someone who is a legal resident of Qatar. They will need to request the visa on your behalf from the immigration authorities in Qatar as international Qatari embassies are not permitted to issue visas.
However there is one work around, upscale hotels and Qatar Airways offer full visa service, for a price, if you book a room with them for the duration of your stay, but be prepared to either present a credit card or cash equivalent of QR5000 upon entry.