Happy 40th birthday, NPR and All Things Considered! There are all kinds of nifty opportunities to congratulate the pubradio network today (May 3), from Facebook greetings to an organized Tweet wave. Also, if you happen to be in D.C., stop by headquarters (635 Massachusetts Ave. NW) at 2 p.m. for a free frozen goodie from the Pleasant Pops truck. And don’t miss the archival photos of all those years ago.