Looking back over the last century, you could make a pretty convincing case that Heinlein has been the most influential of all the authors in John W. Campbell's stable of Golden Age stars. Brian Doherty's essay at Reason magazine is a good once-over-lightly treatment of RAH's iconoclastic libertarian views on a wide range of subjects as expressed in his writing, as well as a useful guide to the influence this alleged "fascist" had on the 1960s counterculture. In a related piece, "L.A.'s Nostradamus", mainly concentrates on the deep (and mostly forgotten) influence Heinlein had on American space exploration; how many of us who watched the first moon landing remember that he starred in CBS' coverage of it? One person who hasn't forgotten that influence was NASA's head of legislative affairs, Bill Brunner, who made that influence clear in his remarks this past weekend at the Heinlein Centennial.
Unlike sqotty, I can't claim that RAH was my entree to science fiction - that place of honor belongs to Madeleine L'Engle, although I haven't read A Wrinkle In Time in decades. I did, however, voraciously and repeatedly devour the Heinlein juveniles on the shelves in my elementary school library, and was introduced to his adult works by way of The Moon Is A Harsh Mistress, which was the cover story in a stray copy of IF magazine that my sixth-grade teacher had among he other paperbacks in her classroom reading shelf. Heinlein's books reinforced a lot of the conservative attitudes I inherited as a military brat, and for years afterward, if I saw something from Heinlein I hadn't seen before, I snarfed it up immediately. I used Heinlein as a yardstick to measure all other SF authors by, which may explain why I was never too enthusiastic about Ellison, Spinrad and the other "New Wave" writers. Sure, there was some interesting stuff in that stylish crowd, but looking back on it forty years later, not much of it has aged very well. Heinlein's works, on the other hand, were built to last and did so quite well.
There's a push on to name one of the new Zumwalt-class destroyers after him, which would be appropriate in a way. While his first service was on the technologically-advanced Lexington, his last ship was the Roper, a "four-stacker" left over from the First World War. Heinlein was proud of his Navy service, and a lot of folks feel naming one of the new 21st-century DD's after him would be just the ticket.