What, you don't remember Ricky Gutierrez as an Oriole? That's probably because he never played a game for the big league club. The Miami high schooler was chosen by the Orioles with the 28th overall pick in the 1988 draft, a pick they received as compensation for failing to sign #1 choice Brad Duvall in 1987. His stock rose when he hit .306 in 49 games at AAA Rochester in 1991, but he hit .252 (and slugged .288!) the following year for the Red Wings. The Birds dealt him to San Diego in August 1992 for veteran pitcher Craig Lefferts. He debuted with the Padres in April 1993, and became the starting shortstop for the cellar-dwelling Friars. He hit .251 with 5 homers and 26 RBI as a rookie with a 78 OPS+, which was a typical performance for him. He managed to stick in the bigs for 12 years, with a career OPS+ of 83. He topped out at 99, when he hit .276 with career highs of 11 home runs and a .375 OBP for the 2000 Cubs.
I don't really have any pithy way to end this, so here's a list of former Orioles that Ricky homered against in his career: Dennis Martinez, Jeff Ballard, Steve Trachsel, Pat Rapp, Kevin Brown, Rob Bell, Gregg Olson, Sidney Ponson, and David Wells. He also went deep against ex-O's farmhand Garrett Stephenson. So...that's that.