Ah, yes. The days of Econet.
I was on one of those YTS iTeC courses as well. Drew wasn't in the Southall branch, was he?!
Anyway, the coolest thing I managed to do (this was back in 1987/88) - having already proficient skills on the BBC Micro since I had purchased one when it came out - was to write a FOR...NEXT loop that would scan memory pages (of a certain range) and print out any ASCII characters found there that were in the alphabet character set range, filtering everything else out.
This was not a program. This was a loop written on the command line, raw, there and then, each command delimited by " : " or " ; ", I can't remember now - preceded only by a *FX200,3 command at the prompt, which wiped all memory at the press of the BREAK button, so no one could see the code I had written, if they tried stopping the loop.
ESCAPE then OLD then LIST? Nope! Remember - it's not a program - it was just written on the command line. BBC BASIC was that frikkin good! I did sometimes hide it in a Red Function key, though, cos I could not be bothered to type the whole loop, whenever I wanted to hack a student or lecturer. And it meant, I could go back to it again, after lunchtime and keep trying. ;-)
Now, why would I be printing pages and pages of memory? Well, because the Econet module stored your log-in password for your account in plain text, somewhere in those particular regions (according to some Econet User Guide I had picked up at one of those computer shows, down at Ally-Pally!)
And if there were no lecturers around, I could quickly write that loop and *NOTIFY it (I think that was the command to send messages) to the machines in the Econet network and have other students run it and watch the screens, looking for any silly/unusual words that might come up that don't belong in those regions of memory. Once found - such as a lecturer's password who had just logged off of that machine - I could log back in again as them and give my account Master privileges (I think it was called), create new Master accounts for myself and tuck them for a rainy day, delete students accounts that had fallen out of favour with my mates, love poems to any girls we fancied, as a log-in greeting etc. Result = king of the jungle!
When the lecturers found out that I was too clever for their establishment, they shipped me off to IBM, for the practical experience part of my YTS course!