Muscat Confidential has a great piece on how urban Gulf economies like Muscat are dependent on access to cheap labor from the Indian subcontinent, peep it:
OK. Lets say you are an Omani and you have a farm up the coast. What you do is apply for visa for say, 10 Bangladeshi farm labourers. You keep 2 of them for the farm, where they will live in a small hovel and work your farm all day. The other 8 you charge say, 500 - 1500 rials for the original visa plus 20 rials a month for their continued sponsorship and labor card, and release them to the wild. They then seek employment however best they can, doing the jobs described above. As their sponsor you pull in a nice lump sum up front (usually borrowed from family back home), plus get 160 rials a month for very little effort; they get to earn what they can and keep most of it. Truly entrepreneurial types can apparently pull in quite a nice bit of cash. Its a huge gimmick. Of course, some of that money will go to ensure you get the visas in the first place through people in the Ministry.
Click on the title link for the whole article, its well worth your reading.