This looks like a thread where I get to feel young...
Sydney 2000 - I was a bit too young to remember these games, but here's an anecdote I've shared before. Pieter van den Hoogenband grew up just a couple streets behind my parents, so I do recall the ceremony we had in town when he returned. I got an autograph and touched his medals as a 5 year old!
Athens 2004 - Van den Hoogenband again, obviously!
Turin 2006 - I mostly recall the impressive showing of a young Ireen Wust.
Beijing 2008 - the Dutch gold in women's water polo was big news here, just like the 4x100 freestyle women. The story of Maarten van der Weijden, who won gold in open water swimming after winning the battle against cancer. All in all, these were very memorable games.
Vancouver 2010 - this memory is more vivid than any other... sitting in the living room with the whole family when Sven Kramer makes a wrong switch and gets dqed. Sad times. There was also the only Dutch medal in a snow event by Nicolien Sauerbrei.
London 2012 - Probably the first Games I started following really closely. Epke Zonderland's gold on the horizontal bar stands out far and above, but also Ranomi Kromowidjojo winning the 50m and 100m freestyle.
Sochi 2014 - Sven Kramer still not winning the Olympic 10.000m stands out sorely again, though the entire speed skating was dominated by the Dutch more than ever.
Rio 2016 - By now it's so recent that it's hard to pick a specific memory. For some reason the lost bronze medal matches of the Handball and Volleyball women come to mind. And the horrible Annemiek van Vleuten crash. But also various international athletes standing out, like Usain Bolt, Mo Farah, Neymar Jr, Katie Ledecky and Simone Biles. Too many to mention really.
PyeongChang 2018 - Again it's hard to choose with the Games being so recent, but Ireen Wust's 1500m and Kjeld Nuis's double come to mind. And Esmee Visser seemingly coming out of nowhere to win gold on the 5000m. Also the first big victory of Suzanne Schulting, let's hope she starts an era like Wust did in Turin 06