In a country that doesn't believe in serving budget travelers, Rob's Guest House is a super option to expensive, impersonal hotels in Oman.
At Rob's - you feel like you are staying with friends. I stayed here and it was a perfect budget way to experience Muscat. Plus - Rob is well versed on Oman (he's a British expat and lived there over 15 years), plus as a bonus he's an expert hiker, diver, and adventure enthusiast. He's eager to provide advice and assistance for your holiday.
You get internet access and breakfast is included! I would recommend that you rent a car though as his guesthouse is not on any public transportation routes, but it is close to the airport. You'll need a car in Oman anyway to get to all of the spectacular places! It's located in the Al Khoud district, north of Muscat.
There is no website - but you can contact Rob directly at firstname.lastname@example.org and get info on staying there.