Just wanted to share three things while scrolling around Baseball-Reference's awesome draft coverage.
==>One player has actually been drafted #1 overall twice, in 1971 and 1975. The White Sox drafted Danny Goodwin out of high school, but he went to college and was later selected first again by the Angels.
==>Among #1 overall picks, high school hitters have fared much better than college hitters. 20 of the 30 different hitters drafted (Goodwin was drafted twice) were picked out of high school, and the top 7 career OPSes of #1 picks belong to high schoolers (Alex Rodriguez, Chipper Jones, Ken Griffey Jr., Josh Hamilton, Joe Mauer, Adrian Gonzalez, and Darryl Strawberry). On the other hand, no college draftee save Goodwin has failed to play 700 career MLB games, and only one other hasn't hit 1000 (Dave Roberts--not the one you're thinking of--709). Meanwhile, 2 high school hitters never reached the majors and 3 others didn't reach 500 career games. That excludes current players (Tim Beckham, Justin Upton, Delmon Young, etc.), of course, and Goodwin.
==>The opposite has been true for pitchers selected #1 overall, as only 2 high school pitchers have ever been picked in that position. One (Brien Taylor) didn't even get a cup of coffee and the other (David Clyde) threw just 416.1 innings in 84 games over 5 seasons. Every college pitcher appeared in at least twice that many games, except for 3 current players (David Price, Luke Hochevar, and Bryan Bullington).
==>Actually, Brien Taylor's story was sort of interesting. He was pretty awesome in high-A ball in his opening season (1992), striking out 187 versus 66 walks in 161 innings, while only allowing 121 hits. The next year he moved up to AA and was still decent, but control issues started to surface, as he walked 102 against 150 strikeouts in 163 innings. Then, he tore his labrum in a fist fight, and was never remotely the same. From the time he returned in 1995 to the end of his career he walked 184 batters in 111.1 innings! He struck out only 88 batters in that span. In one year, he walked 43 batters and struck out 11 in 16.1 innings! And he did all that in lower levels (Rookie and low-A) than he was pitching at before the injury.
==>Ten players have been drafted out of Cretin-Derham Hall HS (where Joe Mauer attended), and not so surprisingly, 5 have been selected by the Twins. Three other notable players have been selected from there, although none by Minnesota: Hall of Famer Paul Moliter was drafted by the Cardinals, Chris Schwab, the only other first-rounder for Cretin, was picked by the Nationals in 1993, and Chris Weinke was drafted by the Blue Jays. He would play six years in their minor league system, reaching AAA, before going to Florida State to play football where he would win the Heisman Trophy.
==>Arizona State University is the only college or high school to have multiple players drafted #1 overall, and they have had 3 alumni picked in the spot: Bob Horner, Floyd Bannister, and Rick Monday.