I must disagree :(
Back in our club in Sydney, we had a fully web-based sign up system, which work absolutely perfectly and made it easier for everyone.
Qtn: In the club trip list, the contact details are listed, so... what is stopping ppl from joining a trip without going to the club night? Please don't see this as a reason to remove contact details, this is one reason i really dislike other clubs.
What the web-based system should actually do, is make it easier for the trip leader to organise the trip, such as having everyone who sign up already listed for a group e-mail, check their profile (with activity/skill level, history, car availability, etc) and have pre-trip gear lists and so on. It shouldn't be treated as a simple sign up form, but more like a tool that will assist those who have volunteered their spare time for the good of others.
E-mail is already a sign up form. Lets think more modern ;)