I knew these kinds of programs were possible, but never really looked into them until recently. A few days ago, I saw a LangaList article (www.langa.com/newsletters/2001/2001-11-01.htm , item #4) that discussed a collection of safe, tiny, and useful programs that can help you make better use of your browser and the web. The site is called the "Bookmarklets Home Page" at www.bookmarklets.com.
The title page gives a brief outline about what bookmarklets are. There is also a link that describes them in more detail. In case you don't pursue this link, there are a few things you should be aware of. Bookmarklets are written in JavaScript, which is a language that has some built-in limitations, intended to prevent dangerous operations. This is no guarantee that a malicious programmer cannot find a way to do something antisocial with a bookmarklet, but there aren't any easy, obvious ways. The www.bookmarklets.com site is currently a trustworthy site in the opinion of site operators that I currently trust. While that isn't likely to change in the future, let the browser beware - especially if you go looking for other bookmarklet sites.
Let me add some a few caveats about bookmarklets. I've found JavaScript to be a very quirky language. Bookmarklets written in JavaScript are very sensitive to browser type, operating system, and the way the page in view is written. Sometimes, I think that phase of the moon, what your astrological sign is, and other unfathomables also come into play. What I'm saying is that some of the bookmarklets that should work - that do work on some systems - may not work on yours. Newer browsers and operating systems usually work better than older ones. You may also find that bookmarklet behavior is quirky; you may not be able to use the "enter" key as a substitute for clicking on an "Ok" button, or you may not be able to use a dialog window more than once. Don't worry too much - there are over 150 bookmarklets at the site. Some of them will work, and I predict you will find a few of these that you really like and use.
Here is a brief sample of some bookmarklets I found interesting. Some let you tweak how the page appears on your computer - these are located in the "Page Look" section. Note that any changes these programs make are local to your machine and are temporary; they can be undone by refreshing the page, so you can play around at will. "Page Color" lets you reset the background color of the page you are viewing, in case the original author chose poorly . You can do the same thing for page text color with "Text Color". "Remove Background Image" will get rid of those occasional backgrounds that make reading page text a chore. "Highlight Links" lets you highlight all the links in the page in yellow. "Hide 468 x 60 Banners" will remove some of those really annoying ad banners from a page; there is also a "Hide All Images" bookmarklet. "Text Font to Verdana" will change a page font to a highly readable font on Windows operating systems (there is also a "Text Font to Arial" function).
There are other types of links, too. "Page Data" tools can check page freshness (often it just gives you the current time, though), list all links, find phone number-like strings, edit a copy of selected text on a web page (for cut and paste) and other functions. The "Navigation" section offers the ability to jump randomly to links on the current page, go to a highlighted non-linked URL as though it were a link, add the top level of the current domain (the home page of the page you're visiting) to your favorites list, jump up one level in the current domain, jump back 2 or 3 pages, and others. If you are a web page designer, there is a section of bookmarklets that can help you, including the impressive "Simple Table Code" bookmarklet.
One other thing you might be interested in - these little programs can be a single mouse click away if you use a recent version of Internet Explorer. It has something called a "Links" toolbar that is an excellent place to put bookmarklets you use often. Search for "links" in Internet Explorer help - Internet Explorer 5.50, describes the process in "To add a page to the Links bar." I believe that recent versions of Netscape have a similar function. Those missing functions you've wished for in your browser may not be missing much longer.
CATBAR - Brain Candy #52 - Bookmarklets / Brian Rock / Nov 21 2001