Like La Boheme, Tosca has plenty of great recordings to chose from.
The Maria Callas, Giuseppe Di Stefano and Tito Gobbi recording is probably the greatest opera recording ever recorded. The three express every word and feeling that the music provides. Callas' Vissi d'Arte is showstopping and Di Stefano's Luevan le stelle is a breath of fresh air. While I listen to this recording I can envision them acting on stage. This is something recordings rarely do. However when you have three great artists who are capable of expressing like them, this is possible. The orchestra is conducted beautifully under Victor de Sabata.
Other recommendations for the role of Tosca include Mirella Freni's, Renata Scotto's and Leontyne Price's. All these interpretations are legendary and are accompanied by the great Placido Domingo who in my opinion is one of the greatest Cavaradossi's.
Madama Butterfly preview she is one of the greatest Madama Butterfly's. Check this DVD out
Roberto Alagna's early recordings display his beautiful voice. This Duets and Arias CD displays the great chemistry that Alagna had with his wife Angela Gheorghiu.
To see the current Met production you can watch the Virgin Classics DVD of 2009's HD transmission. However if you want to hear great singing look elsewhere.
For more infromation on Tosca check out the Tosca Preview.