S2K.com is a very good example of using paid membership. you can access all of the forum for free i.e. the info parts etc and all the stuff that people come on a forum for.
but for those who are a paid member get extra benfits i.e. they can put up for sales ad's (non paying members can buy but not sell) there is also a members only section where only paid members can access. also there are emails inviting members to events like track days and airfield days. paid members get first dibs and a 10% discount. then after a week its opened up to the rest of the club but without the discount. paid members also get a discount with the traders over non paying members.
this does mean they have AGM, the finances and expenditure is posted up each year. they then also have the capital to pay for top notch server and hosting and also have etc IT support. but you have to remember their 1 club incorporates all the s2000 owners from around the world, it is a huge club and people post in their own regional section but when it comes for searching for info. its like being able to browse here, NS, my350Z and every other zed club all at the same time.
so you actually paid double membership, i paid to join the club and to also join the regional club i.e.S2KUK think it was a grand total of £25 all in. which is a snip compared to the £55 i spend to be a member over on EXEC.co.uk the XKR forum. but then they get quarterly magazine, specialist tool hire etc. but thats locked tighter than a gnats bum. all technical info is hidden unless you pay up.