So, recently my chorus has been doing a lot of outside gigs that involve all sorts of operas. As a self-proclaimed TV-child of the 80s with not so interesting taste in music, where would I start, if I wanted to gain as much information about the opera genre as possible? Which operas are a must-know for beginners? Thanks.
I think you’ll find much of Bizet’s Carmen recognizable. Also The Barber of Seville.
Many operatic musical themes have worked their way into movie sountracks and popular culture.
This doesn’t really answer your question, though, does it. Sorry.
You’d probably recognize a few themes from Wagner’s ring cycle–see if you can find a recording of the highlights. Given that the cycle totals 14 hours of opera, you may not want to just jump in with both feet.
The AMG opera page has a short list of highlights that you may find interesting.
That would be What’s Opera, Doc? and The Rabbit of Seville, both directed by Chuck Jones.
Seriously, though, you might want to check out the book Who’s Afraid of Opera? by Michael Walsh.
And don’t forget Rossini’s Lone Ranger Overture, which some philistines refer to as the overture from William Tell. 
Thanks, so far, you guys =D
I’m lucky, living in NYC. Hoping to see a few operas over the summer.
Some “starter” operas are “Rigoletto” and “La Boheme” - both have decent plots and great tunes.
Mozart’s The Magic Flute and Don Giovanni are also great starters. Ingmar Bergman’s film of the former is a delight, and Joseph Losey’s version of the latter is also excellent.
Staying with operas on film, Zeffirelli’s La Traviata is beautifully photographed.
Although I can’t claim to be an opera connoisseur, I believe that the casts of all of these films are top-notch, highly reputed pros.
Another vote for “La Boheme”. As I’ve said before, it has starving artists, love, Paris, tuberculosis–what more could you want? 
“Tosca” is good, too. The end of the first act is one of the great parts of the opera. There’s also a bit of business at the end of the second act involving lighting candles. This may have been originated by Sarah Bernhardt in the play the opera was based on.
When we were in Florence for a study abroad program I dragged four opera neophytes to a performance of La Boheme and left the theatre with four opera fans.
–Cliffy
For absolute beginners, I’d recommend:
Bizet: Carmen
Gershwin: Porgy and Bess
Puccini: La Bohème
Rossini: The Barber of Seville
Verdi: Aïda
Verdi: Rigoletto