Hi, of course. I can highly recommend this brewery, my favorite:
http://www.u3r.cz/en/
It is in the historical center (few steps from "Staromestske namesti") and they always have 3 czech lagers and about three seasonal beers, mostly ales or special lagers.
If you are going to visit Prague's castle, there is my second favorite brewery:
http://www.klasterni-pivovar.cz/index.php?process=34&languageID=2
They have always two lagers and about two seasonal special beers. You can sit outside and watch the monastery (especially nice in the dark, when lighted).
And finally, if you want to try classic pub with many beers on the tap, I can recommend these (but webites are in CZ only):
http://www.zlycasy.eu/
http://www.restauracekulovyblesk.cz/
If you will need help with something, let me know