Off the top of my head, these are some taht have influenced me. Im sure there are others and I'll add them as I think of them.
In no particular order, they are:
Spiritually:
1)"The Kingdom of God is a Party" - Tony Campolo
2) "Who Switched the Price Tags" - Tony Campolo
3) "Too Christian/Too Pagan" - Dick Staub
4) "The Prodigal Hugging Church" - Tim Wright
5) "Nearer My God to Thee" - William F. Buckley
and many books by Schaeffer, Merton, Steve Brown and others.
Politically:
1) "Bobby Sands' Diary" - Bobby Sands
2) "Prison Writings of Bobby Sands, M.P." - Bobby Sands
3) several books by P.J. O'Rourke including, "All the Trouble in the World", "Eat the Rich", "Parliment of Whores", and "Republican Party Animal"
5) various books by Adam Smith, John Locke and others