The most memorable match I had was a couple of years ago with my friend, which lasted more than 3 hours I think and which my friend won in 5 tight sets. It was pretty even (though I think that that's the closest I've ever come to beating him :P). Another great one was a tiebreak against the same friend which I finally won 18-16.
A couple of shots spring to mind that I have to mention. Again, one was against the same friend I mentioned before. He was dictating the point and making me run like crazy from left to right. Finally, he hit a shot to my backhand and came to the net. I was pretty far from the ball, but I'm also pretty fast, so I made there just as the ball was about to touch the court for the second time. There must have been only a few centimeters between the ball and the court, but I was able to slide my racket under the ball (I play a one hander) and flick it for a crosscourt passing shot! It was probably the shot of my life and my friend was amazed that I was able to hit a shot like that from that position.
More recently I hit a similar shot against my kid brother, only that time I managed to lob the ball over him. I also hit another nice lob in that match, he hit a great slice approach shot to my feet. The shot clipped the line, but I was able to half-volley a great lob from my feet over him. He couldn't believe it