In the past I was a member of SIDC - Subaru Impreza Drivers Club,
www.sidc.co.uk - but I s'pose I've kinda grown out of it, lots of boy racers talking about mods, rolling road output numbers and 1/4 mile times... However, the site is genuinely useful for Impreza owners - everything you will ever need to know (especially on the '93 to '99 car) is in the faq.
There's also
www.scoobynet.co.uk, with a forum open to non members (you have to be a paid up member of SIDC to use their forum).
Depending what happens in the not too distant future, I hope to justify membership of
www.quattroownersclub.com and/or
www.pcgb.co.uk ...
granada-and-scorpio-online... now that's sad!