Anyone got any? Got an interview next week for an IT support job at the local uni & can use some suggestions other than the usual stay calm & be yourself bollocks

Panic, and pretend to be someone else? ;)
And remember, if it's a woman, ask her if she's pregnant!
(if you don't follow my suggestions, you should be fine!)

Be keen and enthusiastic. That way if they ask anything technical that you've not had prior experience of, they'll not hold it against you as you've demonstrated the willingness to learn.
Don't wear tan or kharki trousers either - the smallest amount of wee wee leakage in those colours will look like you've totally pee'd your pants and enjoyed it. Sometimes there can be a crusty stain too if you use a hand dryer to try and evaporate the dampness.

Wear smart clothes? I didn't start wearing casual-ish outfit at work till a month in, once you get past the interview you're free to roll in shorts if they will allow you to :].

Be honest.
I'm serious. Every job interview I had where I pretended to be something I wasn't I didn't get.
The job I'm in currently I outright admitted that I disliked a few subjects in school, etc, and actually shown I had a personality. I wouldn't recommend doing this and I class it as a mistake, but I think they appreciate someone who is a little different than every single candidate that has waffled crap that was put on a website somewhere as they probably hear it all day.

Research the potential workplace ahead of time. It helps if you can demonstrate a knowledge of the job and the challenges connected with it. It shows that you are really interested. So google the hell out of the uni beforehand.

It's true, interviewers seem to appreciate forthrightness and enthusiasm more than you would think. Of course, there are some things you probably don't want to tell them, but don't present yourself as a form letter. That makes you look boring.
When I was managing an ice cream shop a few years ago, I found that the more relaxed, lively, and open interviewees made a better impression on me than the subdued ones who were obviously trying hard not to offend me, and they were the ones I generally hired, provided I thought that either one could handle the job (granted working at an ice cream shop doesn't require steep qualifications). Different interviewers have different attitudes, though.
Even if it seems like it doesn't go well, though, you might still be okay. The job I have now (the first "real" job I've had) came out of the worst interview I've ever had.
It's probably a bit late for this, but be careful of what you put on your resume. I had been looking for an entry-level position since college, and I usually interviewed for programming positions. I was taking a networking class at the local tech college, and I put that on my resume under education, because I figured it would show that I was at least keeping busy and trying to improve my skill set while looking for a job, instead of just sitting around. That was a mistake, because every single interviewer I talked to saw that and asked me, usually multiple times, "You know this isn't a networking position, right? Are you sure this is really something you're interested in? Because... this isn't a networking position." Basically, I had to work extra-hard to show that I was interested in the job.
Also, don't be afraid to mention your hobbies on your resume or in the interview if they're potentially relevant to the job. The one thing on my resume that has gotten me more credit and interest with interviewers than any of my training or education, particularly since I didn't have a lot of relevant experience at the time, is the section at the bottom where I mention my Neverwinter Nights script suites and a couple of minor mods and utilities I've written for other games.

Speak clear and motivated. Don't slouch in the chair , even in the waiting room (as they do occasionally get the person there to watch you). Make extra effort on grooming and presentation of self. yadda-yadda, the basic first impressions stuff you probably know about.
If you've done non-work IT stuff, for your own entertainment or study; mention it.
Think of a few examples of a problem you personally were the main person to solve, as it's a question people get stuck on, team-work is good, but they need to know you can work individually, especially in IT support.
From my experience with IT interviews: It's possible they'll throw out a scenario with something wrong in how they said it (deliberately using the wrong terms), to both see if you catch it, and how you correct people on it.
Call your local job agency, they should be able to provide you with a tips-list.

Heh, I'm working as a programmer/placement in US-based oil company and that wouldn't get me anywhere. Now I can kind of wear more casual clothes even though contract states I should be wearing smart :]

Interviews for most non-essential positions are decided within the first five seconds. In practice. Or at least they can be.
So - make eye contact and don't make your first handshake feel like a wet slipper.
Other than that be prepared for a few technical questions if it's a technical position. It's a support job so you need to be able to talk very well and keep calm under any circumstance.

Absolutely. The one thing I would stress is know yourself and be fully confident (but not arrogant) that you are the person for the job. Your perspective employer will not want someone that doubts themselves.

Those are pretty good tips, a few of them I'd not heard before.
I've had a bit of an idea for a while that at the end of the interview when they ask if I have any questions, I would say something like "I like this job, I need this job & I'd be bloody good at this job, what do I need to do to make sure I get it?" but I constantly vary as to whether this is a good straight up enthusiasm thing or borderline begging.

Opinions would vary on that, but I would absolutely make sure to have a list of questions to ask. If it's a panel of interviewers, asking them what they like/dislike about their jobs is useful.
Just as is asking what a routine day is like. Usually it's also a good idea (depending on the setting) to ask what professional development opportunities are available.
Usually employers will want to know that you're interested in furthering your skill set. I try to have at least 5-7 questions in my questions queue, and if they're already covered one, you can find a way to say that.

Don't smoke, chew gum, fiddle with objects like pencils. And always send a followup letter thanking your interviewer :)