I also belong to a Jaguar forum. They have it set up where if a member makes a contribution they get a little color bullet next to their ID.
Contributions are as little as $20. They allow zero commercial advertising and the site is very fast.
I just as soon pay a small donation because I have belonged to other lists that vendors can contribute and get a free ad.
What has happened because of this, the forum has become very political. If some one has a question they get directed by the members to buy such and such from this vendor, its the best blah blah blah.
If a member bought something somewhere else they get ridiculed.
Not that vendors that put ads on forums have junk, its just not the place for it. This is my .02.