C - Miguel Olivio - Even though he will probably hit 8 or 9 he should have ample opportunities to drive in some runs as well as cross the plate with the lineup.
1B - Hee Seop Choi - I don't know what it is about this guy, at one point last year I thought he was finally going to show his stuff, but nope he just decided to totally suck. Hopefully after a year of thinking about how crappy the last 3/4 of last year was he is going to turn it around. He has the power!!! Just has a hard time applying that power to the baseball.
2B - Luis Castillo - I know he probably doesn't qualify as a sleeper, but you can pick this guy up pretty late in a draft (15thish round) and he should pay you above that, with the potential to creep back up into that top 3-4 at 2B.
3B - Dallas McPherson - There is enough stuff on this guy round these boards already, but yeah he should put up some pretty nice numbers and should easily make a run at rookie of the year.
SS - David Eckstien - Another guy who many probably won't call a sleeper, but again you can pick him up very late in a draft and in that new lineup over in STL he can put up some great numbers in the Runs and SB cat, without hurting you in the AVG.
OF - Milton Bradley - If you can get over the fact the guy is a complete idiot most of the day, he has pottential to put up some good numbers, with signs of brilliance surrounded by runs or horridness last year, I like him this year.
Jeremy Reed - If he can secure the 2 spot in this lineup between Ichiro and Beltre his value will just about sky rocket, while you should be able to pick him up somewhere round the 18th round or so, he has the potential to give you some great numbers all around the board (except HR that is)
Ken Griffey Jr - God I hate the fact I grew up in seattle watching this guy and just simply can't help myself for picking him when he is still sitting there in the 19th round of a draft. But comeon Junior, just stay healthy and even if your mediocre you could hit 20 HRs and drive in 75 runs!!!
SP - Woody Williams - He is in SD he pitched pretty well last year, and well i just like the ugy this year, dont' really know why to be honest with you all.
RP - Braden Looper - I know he is far from a sleeper, but this guy has the lineup and the ability to put up some great numbers in the saves cat, he will be coming up behind Pedro, with run support in Beltran. If Reyes and Matsui can stay healthy and get on base for Beltran/Wright and Piazza maybe even Cameron they could score some runs and give this guy enough save ops to score 40+ of them.
Honorable Mentions - brandon Inge, Ben Broussard, Tadihito Iguchi, Aaron Boone, Julio Lugo, Grady Sizemore, Randy Winn (hell who ever hits #2 in seattle), Cliff Lee, Nate Robinson, Ugeth Urbina, Soloman Torres.