So I've been going through and watching the episodes of season 2 for the past couple of weeks and there are a few real classics in there and as well as a couple that weren't very good (either too cheesy or dumb story).

So far I've really liked,

The Doomsday Machine - Great confrontation in this one!
Amok Time - Ah, the classic Kirk/Spock duel!
Trouble with Tribbles - I think everyone knows this one.
The Changeling - This is the one with "Nomad" the space probe
I, Mudd - The actor who played Harvey Mudd was great
Mirror, Mirror - Evil parallel universe Enterprise crew!
Journey to Babel - We see Sarek and Amanda for the first time!


Some that I thought were silly or cheesy,

A Piece of the Action - Enterprise discovers alien planet which adopted 1920's Chicago gangster culture/society.
Catspaw - Kirk, McCoy and Kirk stuck on some kind of gothic planet and are chased by some huge black cat in a castle. LOL

Those are all great episodes. I'd add Obsession and Ultimate Computer to that as well. First is a standout Kirk episode, some really great stuff. I love when McCoy and Spock confront Kirk in his quarters. It was rare to see those types of scenes (real tension or fighting between crew that wasn't alien or disease induced). Ultimate Computer is somewhat of a retread with Kirk "talking the computer to death" (again) but is still enjoyable.

This site provides a few Star Trek-related chuckles:
http://echosphere.net/star_trek_insp/star_trek_insp.html

I just watched "The Ultimate Computer" yesterday and I liked it quite a bit even though I felt that both Kirk and the genius scientist who created the M5 were a bit over the top!

Is the alternate universe in season 2? It's the one with Spock with the grotique or beard and they are all evil.I think its parrallel universe.

That's "Mirror, Mirror"