Registration in Uzbekistan (OVIR)
Regulation on OVIR registration is different now. Fines have been increased so far, that it will not be feasible to do illegal things through bribes. Some hotels are not even authorized to give room to foreigners.
Fine for being without registration or for being caught living at an address where you're not registered is fifty times minimum monthly salary. Minimum monthly salary in Uzbekistan as of (January 2013) is around 25$. If even one day's registration is missing, no OVIR or hotel will continue to register you. 
Remember, the 72 hours you have to get yourself registered applies only from the time you first enter the country. After that, even if you change cities, you have to register immediately.
Registration is so important that its required even from the local citizens who are living in Tashkent, but came from other regions of Uzbekistan. However, fines for locals in violation of the registration law is much less. 
All licensed hotels provide their guests with free OVIR registration slips. It's no use to live in a hotel that unlicensed because the registration slips issued by them are not valid. 
Travelers with tourist visa are only allowed to stay at hotels and guest houses. Travelers with private visa should be registered at the private address. It is easy and simple procedure. You just have to go to the local police station with the home owner where you want to be registered and provide them following documents:

1. Original passports (both, householder and registering person). Your passport will be taken and kept there for 3 working days while they endorse your registration. Householder's passport will be returned immediately. 
2. Documents confirming ownership of the property 
3. Bank receipt about paying 5 USD registration fee 
4. Filled application forms 

There is service office (БЮРО УСЛУГ) in each police station where you can get all the info and help with filling necessary application forms agains a small fee. Just contact them, it would be much easier than filling tons of papers yourself. 
Sometimes people register in one address or city and live at another. Their friends tell, if and when someone checks that you've come to that city or address only today and are going to register yourself just now. In that case there'll be an inquiry, questions will be asked from the neighbors. If you're found at an address where you're not registered after 11pm, even if in the same city as your registration, of course you'll say that you're just a guest there. In that case the same procedure is followed, neighbors are asked a lot of questions, like if they think you're living there or just a guest.

Even the locals who look as if they're not from Tashkent but from other parts of Uzbekistan are often checked in the streets. Bags of even local people are checked in metro stations entry points. Documents are checked inside the metro. If your documents are ok don't worry. Checking of documents is swift and there's no unpleasantness. They are not at all rude, no one will ask for a bribe or try to exploit your situation of being an outsider without any local contacts who can help you. One advantage is that it's totally safe. Of course, follow the common sense procedures like taking care of your pockets, bag, purse in crowded bus, don't take out a wad of dollar bills in public, etc. 

Authorities are very nice polite when checking documents. They're always happy they have guests from another country. But they too have to respect and follow the law and keep Uzbekistan safe and crime free, as it is now.