Great topic Paul

Pretty much anyone on here will tell you that I'm a HUGE Black Crowes fan (going to see 5 Euro dates in 8 days in July) and I guess the jam band scene forms the core part of my music taste nowadays (and has done so for the last few years). Although that depends on how strict your definition of jam band is

I lean towards the more blues-rock end of the spectrum - the Allmans, Derek Trucks Band, North Mississippi Allstars etc - as opposed to bands like Phish and SCI. I love the Grateful Dead's Europe '72 period in particular but have never been able to really get into a lot of their other work for some reason.
I tape and collect live recordings and for me, it all enhances the experience of being a fan. I have 500+ Crowes shows (and that's not counting DVDs, just FLAC) and when the songs are stretched out, played slightly (or drastically in some cases) differently each night, when setlists are mixed up, it's like having 500 different albums to enjoy. This kind of stuff isn't for everyone - and frankly, you won't find too many other fans on here, it's not that kind of forum - but I enjoy musical explorations (at the risk of sounding a bit Spinal Tap) and don't find it tedious at all
Bands like this do have a small but dedicated following in Europe but generally, it frustrates me how little exposure they get here. While I'll always snap up tickets and travel around the country when they do tour here (e.g. two weeks before the Crowes in July, I'm going to see Tedeschi Trucks Band and then Gregg Allman three nights later - we definitely struck it lucky here this year, it's not normally like that), I always think that I'd go and see a lot more gigs if I lived Stateside

And a huge bonus of going to see multiple dates when bands of this ilk do tour here is that the setlists usually vary from night to night - I love going to a show and having no idea what to expect!