A decade ago:
> You are receiving this email because you recently registered for Facebook
...received in May 2006, at the end of my second year of university. A friend had been bugging everyone to sign up, but he was one of the less social/outgoing people, so this is months after Facebook was available at that university.
In November "Alternative Music Society" created a Facebook group — this was the people I spent the most time socialising with. Typically, someone would be organised and would have found an interesting gig, and perhaps negotiated discounted entry, either by phone or email to the gig promoter. They'd let everyone know using a university mailing list, which every club or society was given — joining a fairly casual society like AMS was basically a matter of joining the mailing list. We'd meet up in the student union bar (student-run bar) before heading to the gig; if people were late they'd text.
Then we'd go to a nightclub (perhaps also with a discount), and impress ourselves by getting home afterwards. No-one had a smartphone, though almost everyone carried a mobile phone. A small part of the appeal of the group was confidence in getting home easily: if we went to a gig in some obscure bit of industrial wasteland, someone would know a decent way home by night bus. (Actually not that difficult, London has very good public maps etc, but it would be daunting for freshers.)
Things like houseparties or groups of friends socialising would be arranged face-to-face, by email, or by SMS. Computing students checked their email more often than was healthy, but someone studying maths might manage a couple of days without using a computer, and was best contacted by SMS.
Regarding _finding_ the interesting gigs: most often by word-of-mouth (i.e. SMS/email/face-to-face) but otherwise by being handed a flier while queuing to get in somewhere, from the listings poster on the door of a venue, from venue / band websites, or by subscribing to a mailing list run by a promoter (the person who books a band + venue and sells tickets). Bigger events would also be in the TimeOut magazine listings, or the student newspapers. Last.fm's events section was useful too, they were a new startup but based in London.
A list of all student clubs and societies was on the student union website[1] and was also distributed as a booklet to all freshers.
Online maps and a public transport journey planner were pretty mature, so you'll need to ask someone 10 years older than me how they managed before that :-) (Well, I know: everyone in London would own an "A-Z" — a street map + street index of every street in the metropolis. For night-time public transport, I think the general method was to take a bus to a particular central location — Trafalgar Square — and know the way home from there.)
I had a small digital camera for taking photos, but very few photos went further than my computer. I probably put a few on my LiveJournal, which I used for a while for keeping in contact with friends from secondary school.
Having said all that, just like now it wasn't difficult to find students who moved between lectures and their residence and rarely ventured elsewhere.
[1] Still is, of course: https://www.imperialcollegeunion.org/activities