Petrol - Our cars now run locally produced Biodiesel. No money goes to Saudi Arabia for terrorist funding and mosque building. Oil is a problem though, no practical alternative exists yet. We're working on it. We also cycle where ever possible.
Food - We have given up Indian food and Indian beer. Not a difficult decision as it's so unhealthy anyway.
Airlines - One of our number is a high flying corporate type. His firm are going on a business trip to Hong Kong and the travel department initially booked Emirates, but after some complaining they changed to British Airways at a cost to the Muslim economy of over £14,500.
Corner shops - We no longer use the two local shops owned by the local Ali family, but we use a delightful shop owned by a Greek family slightly further away. A small boycott we agree, but one that makes over £100 per week difference when cigarettes, alchohol, newspapers and misc sundries are taken into account.
Taxis - We used to use the local private hire firm, but they have Islamic script danglies in the cars and Arabic music playing. We now use a taxi firm run by a local English family - they may be East End gangster wannabees, but at least they aren't Muslims.
Shopping - We no longer purchase any goods from Islamic companies or goods produced or supplied from Islamic countries. Simply check the country of origin and put it back on the shelf. Also, make a point of not using any Muslim cashiers, but if you have to, purchase pork products - preferably Danish (see cartoon row). Complaints about Muslims checkout staff always get a friendly response from store managers. (At least in the UK so far. In the US, they have a burgeoning problem with Muslims.)
Between the three people involved in No To Islam!, we estimate that we have deprived around £2500 per month from our local Muslim economy alone. A drop in the ocean, but if dozens of people around the country get involved, then a real difference would be felt by our Muslim brethren. Several of our friends are starting to get involved and their boycott will start to be felt soon.