The following two are among the most enlightening I can remember.

* Richard Hamming's "You and Your Research" http://www.cs.virginia.edu/~robins/YouAndYourResearch.html

* Gian-Carlo Rota's "Ten Lessons I wish I had been Taught" http://alumni.media.mit.edu/~cahn/life/gian-carlo-rota-10-le...

P.S. Ciao Pino! :)