There are a number of very good pages that are devoted to providing comprehensive lists of psychology-related sites.  Most began in a similar manner.  

As I became interested in the Internet as a means of communicating, I began to look for groups of people who shared my interest in teaching psychology.  Hoping to learn more about things, I watched for discussion groups devoted to topics in psychology.  When I heard about a list, I would write down the information — usually on whatever scrap of paper that happened to be at hand.   I joined a list that keep track of new discussion lists and my list of lists grew rapidly. It was not long before I had more scraps of paper than I could handle, so I used a word processor to compile a list of lists.  That effort grew into Addresses of Note for Psychology Faculty and Students (AON).  As I talked to colleagues about the discussion lists  I had found, many of them asked for copies of the list.  Originally, I made up paper copies but later posted AON to Tulsa Community College's ftp site so that anyone could access it at any time and see the latest additions. 

My own MegaPsych site began as a more attractive way of presenting some of the same information that AON contained, and as the WWW began to develop, as a list of neat places that I had found while surfing the web.  I bookmarked them so that I could visit them again later.  As I talked to colleagues about the nifty web sites I had found, many of them asked to see my list.  When I got into web page construction, the obvious first choice of pages to create was my list of bookmarks.  

Other psychologists who have gone through probably very similar experiences, and who developed some of the early, outstanding list of list sites include John Krantz (APS's Internet Resources), Russ Dewey (PsychWeb), Vincent Hevern (PsychREF), John Grohol (PsychCentral), and Warren Bush (Psychology Cyber-Synapse).  These, and other sites developed more recently (see Psychologists on the Web), are all good sources of sites to visit. 
  

Web sites are created or moved every day, so no list can be completely up-to-date.  Sometimes you just have to do the searching yourself.  The web search engines make the task easier.  Recently, mega-search engines have been developed that allow you to search for a topic using several of the major search engines at one time. 
 
 

Search Engines

AltaVista: Main Page - Perhaps the best single search engine today.  I do not think I have ever failed to find what I have searched for using AltaVista.  That is because AltaVista searches the entire page rather than limiting itself to just the titles, keywords, and/or the first few words on the page, as do some of the others.

There are two things you need to remember that will maximize the likelihood of a successful AltaVista search, while minimizing the likelihood of being overwhelmed with hits.  First, if you are using a phrase to search for something, put the entire phrase in quotation marks.  If you don't, every page that includes any of the words in the phrase will be listed as a separate hit.  For example, if I were searching for information on the psychological concept called learned helplessness, I would type "learned helplessness" in the search box.  Second, use the plus and minus signs to make your more inclusive or more restrictive.

I recently did exactly that, with the following results:
Search	Search Phrase:	Hits
1	learned helplessness	174,526
2	"learned helplessness"	1,650
3	"learned helplessness" + human	4,513,323
4	"learned helplessness" - human	824
5	"learned helplessness" - animal	1,312

All-in-One Search Page - All the normal search engines, and a whole lot more.  You could spend an entire day playing with the specialized search engines that are included, and more are being added each month.

Mega-Search Engines

Dogpile - A multiple search engine.  Tourbus recommends it highly. 

Inference Find! - Multiple search engine.

MetaFind - Multiple search engine. 

MetaCrawler - Multiple search engine.

List Search Engines 
Each of these search engines uses a different database, so they can produce very different results.  Try all three. 

The List of Lists - Locate discussion groups.

Liszt - Locate discussion groups.

Tile.Net - Search for discussion lists, FTP sites, newsgroups, and more.

Textbooks Publishers Directory  
PubText International - Locate textbook publishers.