The following is a list of players (50+ ABs, 25+ IPs) that played for multiple teams... Note that some of the names are abbreviated.
HITTERS
Anderson,Brian (Bos, ChW)
Anderson,Josh (KC, Det)
Baker,Jeff (ChC, Col)
Balentien,Wladi (Sea, Cin)
Belliard,Ronnie (LAD, Was)
Betancourt,Yuni (Sea, KC)
Burke,Jamie (Sea, Was)
Cabrera,Orlando (Oak, Min)
Castro,Ramon (NYM, ChW)
Cedeno,Ronny (Sea, Pit)
Church,Ryan (Atl, NYM)
Coste,Chris (Hou, Phi)
Dellucci,Dave (Tor, Cle)
Derosa,Mark (StL, Cle)
Encarnacion,Edw (Tor, Cin)
Francisco,Ben (Cle, Phi)
Francoeur,Jeff (Atl, NYM)
Freel,Ryan (ChC, Bal, KC)
Garko,Ryan (SF, Cle)
Gerut,Jody (Mil, SD)
Giambi,Jason (Oak, Col)
Gonzalez,Alex (Cin, Bos)
Hairston,Jerry (Cin, NYY)
Hairston,Scott (Oak, SD)
Hall,Bill (Mil, Sea)
Hannahan,Jack (Oak, Sea)
Hernandez,Ander (NYM, Was)
Hinske,Eric (Pit, NYY)
Holliday,Matt (Oak, StL)
Huff,Aubrey (Bal, Det)
Johnson,Nick (Fla, Was)
Kotchman,Casey (Atl, Bos)
Kotsay,Mark (Bos, ChW)
Laroche,Adam (Atl, Pit, Bos)
Lopez,Felipe (Mil, Arz)
Lugo,Julio (StL, Bos)
Marson,Lou (Cle, Phi)
Martinez,Victor (Cle, Bos)
Mclouth,Nate (Atl, Pit)
Milledge,Lastin (Was, Pit)
Miller,Corky (Cin, ChW)
Morgan,Nyjer (Was, Pit)
Rios,Alex (Tor, ChW)
Rodriguez,Ivan (Hou, Tex)
Rolen,Scott (Tor, Cin)
Salazar,Oscar (Bal, SD)
Sanchez,Freddy (SF, Pit)
Thome,Jim (LAD, ChW)
Wilson,Jack (Sea, Pit)
Wilson,Josh (Arz, Sea, SD)
Woodward,Chris (Sea, Bos)
Zaun,Gregg (TB, Bal)
PITCHERS
Ayala,Luis (Fla, Min)
Beimel,Joe (Was, Col)
Bennett,Jeff (Atl, TB)
Betancourt,Rafa (Cle, Col)
Boyer,Blaine (Atl, StL, Arz)
Breslow,Craig (Oak, Min)
Broadway,Lance (NYM, ChW)
Burnett,Sean (Was, Pit)
Cabrera,Daniel (Arz, Was)
Contreras,Jose (Col, ChW)
Eaton,Adam (Bal, Col)
French,Luke (Sea, Det)
Garland,Jon (Arz, LAD)
Gaudin,Chad (SD, NYY)
Gorzelanny,Tom (ChC, Pit)
Grabow,John (ChC, Pit)
Grilli,Jason (Tex, Col)
Hanrahan,Joel (Was, Pit)
Hart,Kevin (ChC, Pit)
Herges,Matt (Cle, Col)
Hernandez,Livan (NYM, Was)
Kazmir,Scott (LAA, TB)
Kensing,Logan (Fla, Was)
Lee,Cliff (Cle, Phi)
Macdougal,Mike (Was, ChW)
Mahay,Ron (KC, Min)
Masterson,Justi (Cle, Bos)
Meredith,Cla (Bal, SD)
Misch,Patrick (SF, NYM)
Mortensen,Clayt (Oak, StL)
O'Day,Darren (NYM, Tex)
Padilla,Vicente (LAD, Tex)
Pavano,Carl (Cle, Min)
Peavy,Jake (SD, ChW)
Pena,Tony (Arz, ChW)
Penny,Brad (SF, Bos)
Perez,Chris (StL, Cle)
Rauch,Jon (Arz, Min)
Richard,Clayton (SD, ChW)
Rincon,Juan (Col, Det)
Roenicke,Josh (Tor, Cin)
Sherrill,George (LAD, Bal)
Smoltz,John (StL, Bos)
Snell,Ian (Sea, Pit)
Springer,Russ (Oak, TB)
Tomko,Brett (Oak, NYY)
Vargas,Claudio (Mil, LAD)
Veras,Jose (Cle, NYY)
Washburn,Jarrod (Sea, Det)
Weathers,David (Mil, Cin)
Wells,Kip (Was, Cin)