Others forgotten:
Watched supergrass in Shepherd's Bush, as we were having a wee me and a mate were joking about The band bush being from the area and that talentless Gavin Rosdale who by that time was rightly a forgotten Nirvana lite. Out of the stall stepped none other the man himself. I almost felt bad about it, but I'm sure he consoled himself with the huge profits from his (and his missus) multi million selling albums, despite an utter lack of credibility, integrity or respect.
Stood next to someone from Blur apparently (oddly at another supergrass gig), I didn't even notice them.
Sat opposite from most of Kasabian and the drummer from the cooper temple clause, in a weatherspoons near Brixton academy. Both bands were supporting the black rebel motor cycle club, they got the coopers drummer totally smashed, at the subsequent gig the coopers drums were unsurprisingly, all over the place, still the coopers sounded better than Kasabian to me.
Gave £10 to the not entirely famous DJ rubbish and sometime cassette boy collaborator, explained it was for his album which I had acquired through other means, seemed a jolly good fellow from peckham.
Not sure I've deliberately acknowledged anyone specifically for being famous, I can't see the point, mostly the whole British reserve is likely the best approach imho.