I'm also re-reading Niven's Ringworld series, as a bridgehead to the rest of his Known Space material; I've never gone beyond Ringworld before. I'm in the third book at the moment. https://en.wikipedia.org/wiki/Known_Space

Not so much hardcore technology stuff, but here's a reading list I put together a while back, aimed at IT executives, CIOs, etc.

http://fogbeam.blogspot.com/2013/05/10-essential-reads-for-c...

http://fogbeam.blogspot.com/2013/05/essential-reading-for-it...

Not on that list (I had not read it at the time), but one I'd highly recommend is Eric Beinhocker's The Origin of Wealth. http://www.amazon.com/The-Origin-Wealth-Remaking-Economics/d...

Speaking of Koenig, I also like his C Traps and Pitfalls (1989).

Sedgewick's Algorithms is excellent. My copy is 30 years old, but I know there are newer editions. I believe it's multi-volume now.

I liked two by Richard Stevens: Unix Network Programming and Advanced Programming in the Unix Environment.

And I like Bentley's Programming Pearls.

These are all old, but I'm old. :-)

Addenda: I've really liked everything I've read by Brian Kernighan. K&R is my favorite programming book bar none.

Data Reduction and Error Analysis for the Physical Sciences by Bevington and Robinson. Very approachable introduction.

div grad curl and all that by Schey. Read it before taking Fields, instead of after like I did.