I had the fortune to actually be recommended a GOOD anime by mDuo. If you haven't seen ARIA the Animation yet, I would recommend it if you are a generally cool and laid back guy or gal. It's big on the "slice of life" style, which in my experience has become synonymous with "pretty music." Kokoro Library, Yokohama Kaidashi Kikou ~Quiet Country Cafe~, Windy Days, etc. all have these wonderfully relaxing soundtracks. Since I enjoyed ARIA's so much, I feel like giving it a nice review.

The music is done mostly by
Choro Club, a nice acoustic trio who also did the music for Yokohama Kaidashi Kikou's Second OVA [Look for both OVAs, but read the excellent manga first or they won't make sense!]. That's where I first heard their music and I was amazed at how wonderful they sounded. Of course, on that OST, Taku Iwasaki also worked on it, and orchestrated Choro Club's songs, which was EXCELLENT. Unfortunately, no orchestration here, just Choro Club, but that's fine with me!
The OP and ED, strangely, don't seem to be included on the OST, but there are singles available for each song. The OP is done by Yui Makino, and the ED done by Round Table featuring Nino. Every time I hear a Round Table song, it's always featuring someone called Nino. Why don't they just make Nino part of their band?
[mDuo13's note: I was wondering the same thing!] Yui Makino's song is nice, it's slow and smooth, and fits the show well. During her song, they actually show different things about the town in the anime, and sometimes the characters even have conversations above it. So it's not a very traditional OP sequence, but it still works. More time for characters! The ED theme by Round Table [featuring Nino, of course] is the most upbeat and poppy song you'll hear on the show, but it's quite nice. Actually, if you've heard any of the other billion ED themes they've done, this one is pretty downtempo compared to their usual creations. There's one more thing I thought was worth mentioning. During the show, one of the undines is famous for her beautiful singing voice. I'm glad they didn't hire a VA that sucked at it [Hi, BECK!], in fact I really enjoy the song. It's available on the OST and it's called "Barcarolle."
I have a few small beefs, however! For one, throughout the show, there are versions of the OP and ED with different lyrics. I would've liked to have had those versions. Also, while watching the show in the first few episodes, I couldn't help but think Choro Club was reusing old tricks from music they've done in the past. I kept thinking they reused stuff from the YKK OST, but after watching the whole of ARIA and downloading the OST, I realize it's not an overwhelming problem. Their music is similar mostly from their playing style and instrumentation. SORRY I EVER DOUBTED YOU GUYS!
I heartily recommend the OST, and the two singles if you can find them, especially if you're looking for some nice relaxing music, a thing I am constantly searching for.