Their surprising appearance at the Coachella Valley Music and Arts Festival in 2006, playing for the first time in the now-iconic glowing pyramid, heralded by Close Encounters of the Third Kind chimes.
Their surprise appearance at the 2008 Grammys during Kanye West's performance of "Stronger". The album version of the song uses samples of Daft Punk's song "Harder, Better, Faster, Stronger"; in the Grammy show, Daft Punk themselves appeared and performed that part of the song live.
To clarify what makes this a true Crowning Moment, instead of just Awesome: This was the first time ever Daft Punk had appeared live on television (they'd been on TV before, but always pre-recorded).
After several years worth of award snubs, Daft Punk gets nominated for 5 Grammys for the 56th Grammys, including Album of the Year and Record of the Year, and winning at ALL of them.
Their second live televised performance ever was beside Stevie Wonder, blending "Get Lucky" with a number of other memorable songs. They essentially turned the Grammys into an enormous dance party.
Appearing pretty much As Themselves in TRON: Legacy and turning into a One-Scene Wonder. According to the Disney executives, they not only showed up to the meeting in their robot cosplay, but spent the meeting (over pancakes) asking them all kinds of questions about the movie to see if it would be "done right".
Getting Leiji Matsumotoout of retirement to not just animate some music videos, but an entire album as a silent film. The end result, Interstella 5555, is distilled awesome.