Free:

Supreme Court of the United States - 2007 Slip Opinions of the Court
http://www.supremecourtus.gov/opinions/07slipopinion.html

This site contains the "slip", or first officially-printed version, of decisions of the US Supreme Court.  Opinions are generally released on the website in the afternoon of the decision, in Adobe Acrobat format.  Although Mark Twain was of the opinion that "No man's life, liberty, or property are safe while the legislature is in session", the members of the legislature, unlike US Supreme Court Justices, don't serve for life.  Who knows what will happen while the Court is in session?  At least you can find out at this site what's just become legal or illegal.

Bartleby.com - Great Books Online
http://bartleby.com

This site allows you to read or search several publications, including:

•  the American Heritage Dictionary (current edition), the Columbia Encyclopedia, and three collections of quotations;

• specialized references such as the King James Bible, Gray's Anatomy, and Strunk's Elements of Style;

• various works such authors as Shakespeare, Aesop, Chesterton, and many others.

FindLaw - Laws, Court Decisions, and General Legal information
http://www.findlaw.com/casecode/

This site contains the US Code (US Federal law), the US Code of Federal Regulations (rules established by Executive Branch departments), the Federal Register (proposed or newly approved Federal Regulations), the laws of the several US States, as well as general legal information and assistance in finding legal representation.

iLoveLanguages - places to find language resources
http://www.ilovelanguages.com/

This site is not a resource in itself; rather, it contains a comprehensive catalog of language-related information.  Generally, easier to use than a general index like Google or Yahoo when looking for specific language-related information.

PoemHunter.com
http://www.poemhunter.com/

This site contains about 100,000 poems, browsable and searchable, from both widely recognized authors and from people you likely never heard of. It also has lyrics to 40,000 songs, and a collection of quotations.

RhymeZone
http://www.rhymezone.com/

Writing your own poems?  Stuck for a rhyme?  Go to this site and your problems may be ended - at least in rhyming.

stats
http://www.stats.org/

This site, maintained by George Mason University, researches the statistics presented by news media.

Free with points, or else pay-for-access:

Experts Exchange
http://www.experts-exchange.com/

OK, just skip this one if you're not a computer geek. ;>  If you are a computer geek, here's your chance both to show off what you know - and get increased access for showing off in the bargain - or to ask those questions that the software providers never seem to be able to answer even for fifty bucks a question.  There is a limited access option, with ads, available for free.  By accumulating points (for being an accurate show-off) - or by taking the shortcut and paying (US$ 99.50 / yr as of Jan 2006) - you get access to premium services such as unlimited questions and no ads.

These sites want money - but look at what you get!

MyWire
http://www.mywire.com/

Formerly known as KeepMedia, This site is an aggregator of magazine content. This service includes (so far) over 300 periodicals, including Newsweek, US News and World Report, Business Week, Variety, Reason, Mother Jones, and The New Republic. There are also some newspapers, such as USA Today, the Detroit Free Press, and the Philadelphia Inquirer, and trade-specific magazines, such as Accounting Today, Cement Americas, and the ever-popular Supply Chain Management Review.

The catch is, the current issue of any given periodical is not available. This way, the magazine doesn't wind up (hopefully) going out of business. On the other hand, you get oodles of back issues, full search, and you don't have 'em cluttering up your home.

On the yearly plan, MyWire charges (as of Jan 2008) just under US$ 50 / yr for the service - less than the cost of two magazines for a year (or in some cases, less than the cost of one magazine for a year).

questia
https://www.questia.com/

This site is so not kidding.  About the size of the library, I mean.  Over 60,000 books, fully searchable and browsable.  100 magazines, mainly not overlapping with KeepMedia; and over 500 journals, also fully searchable and browsable.  The site also provides a way to quickly organize multiple research projects and to create citations to the source media easily and quickly.

On the yearly plan, questia charges (as of Jan 2008) US$ 100 / yr for the service.

Safari
http://safari.oreilly.com/

Another item for those who are not computer geeks to skip.

For the rest of you... isn't it a pain when you're sitting there programming, or configuring a network, and you just don't have the proper instructions for what you're trying to do - or you have them somewhere, buried under what seems to be 20 tons of coax cable and those old 300-baud modems the department never threw out?  Safari is the solution to that problem.  Questia (above) doesn't cover computer science books.  Safari only covers those.  Over 1300 of those, including all the O'Reilly books.

There is a two-tier pricing structure: the Basic Bookshelf service allows access to up to ten books at at time, and costs US$253/yr. Each book placed on the "shelf" must be there for at least 30 days before removal; I've found this option sufficient for my needs. There is also a Library service which does not have the 30 day limitation and which offers training videos as well as pre-publication books; this costs US$473 a year and is good for those who work on the bleeding edge of computer technology.

It may seem a bit pricey... but if you're an alpha geek, just look at how much you spent on computer books in the past year - and just see if you can find them.