Replace the stock factory thermal paste with a good aftermarket one, Gelid GC Extreme - I used it on my PS3 Slim 1st gen after a year I bought it, and I run my PS3 with the top cover off, the fan never once goes faster than initial boot up speed. I also removed the front HDD plastic cover to give better ventilation - HDD gets very hot when running for long periods.
The blue LED fans were taken from an unused USB laptop cooler, they were sucking the hot air out instead of blowing to help cooling the rear PSU unit.
I did once ran it for almost a week non stop, downloading GT5 videos, demos and play heavy games like GT5, GTA IV, Dead Space, Heavy Rain, Battlefield Bad Company2, and MGS4 for hours. When I don't play games, I play music and watch movies via streaming from my laptop.
The only maintenance I did is cleaning the fan and inner parts every month.
It's been 3 years since I owned it, never missed a beat.