Binoculars are a great way to get started in observational amateur astronomy. These instruments are relatively inexpensive amd are eminently portable and easy to use. A surprising number of celestial objects including many binary stars, open and globular star clusters, nebulae, and even some galaxies can be detected with binoculars. Scanning through the heart of the Milky Way with binoculars from a very dark site is a truly fantastic experience.
I recommend purchasing a 10x50 (i.e., 10 power and 50mm aperture) binocular for astronomical use. A 10x50 binocular is usually not overly heavy for most people to hand-hold and provides a 5mm exit pupil that will be appropriate for most observers when age and observing site darkness are taken into account. Celestron, Nikon, Orion, and Pentax are good mid-price brands to consider. Something along the lines of the Orion Ultraview or the Celestron 10x50 Ultima would be a good choice. There's a comparison review of a 10x50 Orion Vista with a 10x50 Carton Adlerblick at http://www.cloudynights.com/item.php?item_id=1434
Look for a binocular with at least 14mm of eye relief if you must wear eyeglasses while observing.
Most binoculars are made in China nowadays and are sold by a variety of vendors under a host of different brand names. Some of them have surprisingly good optics.
Information on binoculars suitable for astronomical observing can be found at the following sites:
http://web.mac.com/jay_reynolds_freeman/AstroPDFs/j.r.f.binocular.html
http://www.astunit.com/faq/binocular.htm
http://www.rca-omsi.org/binos.htm
http://www.chuckhawks.com/binocular_basics.htm
http://web.austin.utexas.edu/edcannon/binoculars.html
http://members.tripod.com/irwincur/binocular_primer.htm
http://www.prc68.com/I/Bino.shtml
Binocular Astronomy by Craig Crossen and Wil Tirion, Touring the Universe through Binoculars by Phil Harrington, and Binocular Highlights by Gary Seronik are three good books on observing with binoculars.
http://www.willbell.com/handbook/HAND2.htm
http://www.philharrington.net/sw8.htm
http://www.shopatsky.com/prodinfo.asp?number=59430
This website discusses a number of deep-sky objects that can be seen through binoculars. A few more good objects are mentioned at http://www.backyard-astro.com/deepsky/bino/homeb.html
A list of binocular objects is included with each monthly Evening Sky Map at
http://skymaps.com/downloads.html
The Astronomical League's Binocular Messier, Deep Sky Binocular, and Southern Sky Binocular lists include many of the best binocular deep-sky objects:
http://www.astroleague.org/al/obsclubs/binomess/binomesb.html
http://www.astroleague.org/al/obsclubs/dsbinoc/dsbnlist.htm
http://www.astroleague.org/al/obsclubs/sskybino/ssbinoc1.html
Binocular Deep-Sky Objects by Season:
Summer
During the summer, the open clusters M6 and M7 in Scorpius are good binocular objects as well as NGC 6231. Be sure to have a look at the Coathanger asterism (Collinder 399) in Vulpecula. In the same constellation, M27 stands out well in larger binoculars. M39 in Cygnus is a large, coarse open cluster that looks good in binos. The same goes for IC 4665 in Ophiuchus. There is also, of course, the so-called Binocular Double Cluster, which consists of NGC 6633 (Ophiuchus) and IC 4756 (Serpens).
Autumn
In the autumn sky, in addition to M31, the large open cluster NGC 752 and the nearby Golf Putter asterism in Andromeda are worth a look. M33, the Triangulum Galaxy, which can be a difficult object in less than dark skies, is almost the same distance to the southeast of Beta Andromedae as M31 is to the northwest. Just north of the Double Cluster (NGC 869 and 884), which is itself an excellent binocular target, lies the charming Muscleman Cluster (Stock 2), which was nicknamed by my friend John Davis. Two other fine objects in Perseus are Melotte 20 (the Alpha Persei Association) and M34..
Dave Mitsky