This forum has by far and away the best ethos to it. Sponsorship on other forums has just been a breeding ground for inter-company slating and back biting. Just look at the golfmkv forum in-fighting that goes on!!
Advertising can be a good method of generating money for a forum, but again I believe it would ruin the overall enjoyment and feeling of the site as being a close knit community of like-minded enthusiasts that it is at the moment.
Keep up the good work fella's
