The books are available in libraries, or on microfiche (e.g., the University of Michigan Microfilm collection), and bits and pieces are online at different web sites. The New England Historical and Genealogical Society has an index online at their www.newenglandancestors.org subscription web site for most of these tan books.
Now there is another - FREE - option for researchers. Many volunteers have participated in the copying, scanning and transcription of the vital records of many towns, and these are being posted at the http://www.rootsweb.com/~maessex/VitalRecords/ web site, under the direction of John Slaughter. The web site notes:
In addition to the transcriptions, part of the project is putting images of the pages online. Where these are done, they are linked from the transcriptions. These are there for the researcher to print for documentation purposes. The transcriptions are intended to be a research aid and are not the source. Use the images for that. Where images are not yet online, they can be requested from us.
The vital records pages are still under construction and will be for quite a long time. The length of time will be determined by how much time and money I can devote and how many volunteers help in doing this work.
So far the transcribers have 324,498 births, 216,778 marriages and 139,609 deaths for a total of 680,885 transcribed records.
Each set of town VRs being scanned and transcribed are listed on the web page. Each town has a link to the records, and the transcribed records have links to the scanned pages. This system is excellent!
The really important addition to the knowledge base is the Surname index which lists the towns for each surname, and provides links to the town records. At a glance, you can see which towns have the surname you're interested in. Excellent resource!
There is more explanation at the web site - read all of it. This is a tremendous project undertaken by volunteers, and the organizers and volunteers should be saluted and hailed for their effort. The effort is still in work and more transcriptions and indexing will be provided over time.
Bravo to John Slaughter and his volunteer team for a job really well done providing free primary information (based on original source material) to the genealogy world.