I gave you some recommendations before, but here are some resources where you can discover for yourself what you might like:
4AD is one of the oldest and most respected indie label in the world, having been the home of countless famous bands like Cocteau Twins, Dead Can Dance, Bauhaus, Clan of Xymox, Frasier Chorus, Pixies, Throwing Muses, This Mortal Coil...etc:
http://www.4ad.com/
http://en.wikipedia.org/wiki/4AD
Temporary Residence is an excellent indie label, home of Caroline Lufkin:
http://temporaryresidence.com/
http://en.wikipedia.org/wiki/Temporary_Residence
Minty Fresh is also an excellent label, having released some of my favorite bands like Ivy and White Shoes and the Couples Company:
http://www.mintyfresh.com/
http://en.wikipedia.org/wiki/Minty_Fresh
Other resources:
http://www.indierockcafe.com/
http://indiecharts.com/Indie_Music_Genre_Charts.php?Genre=Indie
List of top 50 American indie labels:
http://www.billboard.biz/bbbiz/industry/indies/billboard-pro-s-d-i-y-50-indie-labels-part-1005317562.story
http://pro.billboard.com/content/50-best-indie-labels-america-part-ii
If you really want to educate yourself on music in general, you kind of have to go beyond the typical casual fan mentality and do some research. Look up the indie artists you do like and see what record labels they're on, and then see if the label has other similar artists you might like. Also, do wiki searches, or general google searches for "bands that sound like so-and-so" will get you other similar artists. There are also lots of forum posts like "Can someone recommend other artists or bands that sound like so-and-so?" Googling phrases exactly like that will get you tons of hits.
Also, most people tend to be quite ignorant when it comes to the very wide range of musical genres available out there. Many people seem to think there's only hip-hop, rock, pop, metal, RnB, country, techno, classical, and jazz, and that's it. There is so much more out there if just allowed yourself to be adventurous and explore. There are many sub-genres or hybrid genres that are very interesting, but not many people know about them, despite them having existed for decades. For example, how many people really listen to genres like:
Acid jazz
Trip-hop/Down-tempo
Progressive house
Electro
Breakbeat
Progressive rock/metal
Fusion
Jazz fusion
Dark Wave
Shoegaze
Art rock/pop
Post rock
Ambient
And those are some of the most well-known and popular genres outside of the mainstream. There are a ton of others:
http://en.wikipedia.org/wiki/List_of_popular_music_genres
http://en.wikipedia.org/wiki/List_of_music_styles
Every time I hear people complain about how there aren't enough good music out there, it's always the same thing--as soon as I ask the person how wide of a range of musical styles and time periods he's actually explored seriously, it becomes evident that the person is fairly ignorant of what's actually out there, and have never tried to be resourceful in the way he searches for new music. Or they just complain about how there's so much stuff out there that there's no way to know what's good. Well, that's what forums are for--to ask for recommendations, and now you have some very comprehensive resources to use in your hunt for good music. You really do have to put in the time to actually hunt though, because ultimately, only you know what you might like. So go listen to a ton of demo clips on amazon, cdbaby, myspace band pages, and so on. If you hear stuff you like in TV shows and movies, look up who the artist/band is. You have to be active and willing to put in the time and energy to look for the wonderful things out there in the world--they won't come to you on their own--it's up to you to find them.