As noted by Tim at Pirates Prospects, the Pirates have made two more minor league signings: outfielder Brett Carroll and right-handed reliever Roman Colon. Neither has been added to the team's official list of NRIs yet, but it's possible that the list might not be updated until the team has formally announced the signings.
Of the two, Colon probably has the slightly better chance of making the majors this year. Originally a Braves prospect, he's spent parts of six seasons in the majors, including three games for the Royals in 2012. Current Pirates assistant GM Greg Smith was working for the Tigers as a special assignment scout when Detroit acquired Colon (and Zach Miner) from the Braves in the Kyle Farnsworth deal, so Colon's signing this spring may be a result of that past connection. Colon is a big guy, listed at 6'5" and 245 lbs., and he's got the traditional thick lower half of a pitcher of that size. His fastball touches 95, and he complements it with a slider and a splitter. He put up decent (though not exceptional) numbers at AAA last year, followed those up with decent (but not exceptional) numbers in the Dominican Winter League, and concluded his year with two games in Mexico. There are a couple of bullpen jobs that should be open for competition this spring, and while Colon isn't exactly at the front of the pecking order, it's not out of the question that a hard thrower like him could see some time in black and gold this year if he looks good in the early going.
Carroll is a former Marlins prospect who has made brief MLB appearances in six seasons, most recently five games with the Nats in 2012. He's a right-handed batter and an enthusiastic, try-hard type who's best suited defensively for right field due to a lack of range, though he's also spent some time in center. His build is a bit stumpy, with a big barrel chest, and he's got an extremely strong throwing arm - see this clip for one fairly impressive highlight. Offensively, his game has been held back by problems with contact, which keep him from hitting for much batting average, but he does offer a little power and borderline-acceptable plate discipline. The Pirates' outfield picture this spring is going to be crowded, with players like Tabata, Presley, and Sands fighting for bench jobs, alongside a fairly interesting NRI in Felix Pie. Being right-handed can't hurt Carroll's chances, but he may still need to bide his time at AAA and wait for an injury or two in order to have a real chance at a spot on the 40-man roster.