May 1st 2014 marks the 20th anniversary of the day that Ayrton Senna lost his life in a Formula 1 race at Imola Italy. Most race fans would rank him at or near the top of any list of greatest drivers of all time, so there isn't a lot that I can add to that. Just for winning three world championships I'd put him at the top of my list also.
Besides his accomplishments on the track, he also made a big difference in increasing the safety of racing in F1 today, probably mostly by the safer design of tracks and that F1 no longer races at Imola too. Happily we can say that there have been no other fatalities during race weekends (practices, qualifying, and races) for 20 years in F1.
I guess my main thought is to stay safe in every car I drive, and always look out for the other drivers, including every day driving.
If you want to catch up on the highlights of Ayrton Senna's career, I'd recommend this Formula 1 webpage and their selected 20 highlights: Ayrton Senna on Formula 1.com