There are several nice options that come out of the professional studio environment. I can personally recommend passive ATC 7s or 11s and active 16As and 20As. These are pro studio monitors designed for small mixing rooms with nearfield sound. Very neutral and honest of the recording source. Tannoy also makes a similar line. I only see them in the UK at home studios of musician friends and you should inquire about their US distribution. ATC products are represented by a pro equipment distributor out of Las Vegas and they are wonderful to work with in sizing the equipment to a room.
Blue Sky Audio also makes several studio grade products. Their active EXO is a steal at $200 to 400 and is one of the few products that really compressed MP3 files sound great on. I always use these as a reference speaker to preview iPod oriented mixes.
If you are looking at more traditional consumer home electronics, Zu Tones are a very efficient speaker that can be played in small spaces. I do not own these, and they are sold directly via www.zucable.com under a 60 day return policy, but I have heard them at numerous shows and was impressed at their ability to recreate music at low volumes. Other small speakers are Paradigm Atoms and Studio 20s which deliver a great deal of musicality for their money. If you desire a more relaxed British sound, with good mids and vocals, I would recommend the new B & W 685 speakers, a Chinese made version with many of the same characteristics as their noted 800 series.