There are loads obviously, Zidane against bayern leverkusan in the final,
gerrard -olymiakos or west ham
but my all time favourite has to be ronaldo for Barca
http://www.youtube.com/watch?v=Ow3yzlPZZ_s&feature=relatedOr
Eto'o for Barca against Panathanikos for his 3rd hat trick goal, the audacity to go the shot that early for a hat trick shows what he's all about.
http://www.youtube.com/watch?v=FULPhCRVLdAImagine getting put through with the pace to make it a one on one for your hat trick and you go for that effort, speechless