I don't know any forum that is as busy as it was 2-3 years ago. In fact I know other forums that 5 years ago were 20 times busier than us, that have now ceased to exist.
I know some on here used to use thedvdforums for example. You could post a topic on there before you went to work, and by the time you got in it would be on page 5 or 6, even having had a few dozen replies. Now looking at the first page, there are threads there that haven't been replied to for 4 days. That used to be one of the busiest UK forums.
TRF is the same, front page, 22 threads, some not replied to for a few days. We are just a few threads behind them, but they do a lot of marketing, and a lot to promote the site, as it makes money for them, so I would expect them to be busier. They aren't as busy as they were though.
Twitter and Facebook have pulled people away from forums. Even Digitalspy etc (which were massive!) seem less busy than before.
Plus people change, grow up etc. I know in the past we had members at uni, or single guys/girls, who might now have a family, have jobs and don't have the time to read/post anymore, and maybe don't have the disposable income to gamble with, and thats not taking into account the recession!
It's not that easy to attract new members either. People now grow up with facebook, not forums. Racing is also a minority sport, its not like football where you have 30000-100000 potential members in each town.
Having said that at some point this year I do intend changing a couple of things. Assuming no one has any objections I'll be changing the main forum so you can read it whilst not logged in, at the moment you have to sign up to read it, which can put people off. I also want to try and install
http://www.vbadvanced.com/ which again, should have a positive effect on member numbers. Thats probably a couple of months away though.
Having said all that - I have never understood why Saturday's are so quiet. I always would have thought it would be the busiest day of the week, but it's always been about the quietest. Maybe 10 years ago when a lot only accessed the internet through work, but most people have it at home, on phones or mobile broadband for laptops now don't they?
I don't think we are do too bad TBH. We are less busy than we were 5 or 10 years ago, but so is everyone. I do nothing at all to attract new members, yet we do still get some. We are still busier than a lot of racing forums, and not far off the ones that are busier. Obviously betfair etc will have busier forums, but thats because they have other means of attracting members.