Top 13 Most Useful Bookmarklets

• Mr Clay's My Page (Source)
  This bookmarklet lets you select elements on the page to remove/edit. It's similar to PrintWhatYouLike, but the element selection is easier to navigate with the keyboard.
• ManInBlue's FormTextResizer (Source)
  Some modern browsers, such as Google Chrome, let you resize the textareas and input fields natively. This bookmarklet was written before that, and it lets you resize any textarea or input field on the page.
  
• Toggle Editable
  Based on Squarefree's "edit page" bookmarklet (Source), this bookmarklet lets you switch the current webpage between editable and non-editable.
• Image Zoom
  Based on Squarefree's "zoom images in" bookmarklet (Source), this bookmarklet lets you input the scale factor. E.g. A scale factor of 2 makes all images twice as big. While a scale factor of .5 makes them ½ as big.

• Translate Selection To English
  Based on Google's own "Add to Google Bookmarks" bookmarklet (Source), this bookmarklet takes the selected text and translates it into english in a popup window.
• Paint Regexp
  Based on Squarefree's "highlight regexp" bookmarklet (Source), this bookmarklet allows you to not only specify what regular expression to search for, but also asks you what color you would like the matches to be highlighted in.
• Google's Add Event (Source)
  This bookmarklet lets you "quickadd" an event to your Google Calendar.
• Edit Tab Title
  This bookmarklet lets you edit the current tab title. (Probably doesn't work in all browsers.)
• Chrome Notepad
  This bookmarklet is based on a variety of bookmarklets users posted at Jose Jesus Perez Aguinaga : One line browser notepad
• Crop4Print v0.5 (Source)
  This bookmarklet hides everything on the page except for the selected area. It also provides a (non-printing) "return to page" button below your selection.
• frmget (Source)
  This Squarefree bookmarklet changes all "Post" forms on the page into "Get" forms.
  Squarefree gives a little background information:

  There are two types of forms on the Web, Get forms and Post forms. Most search forms are Get forms, which include form data as part of the URL in a format like ?var=value. Forms that have a permanent effect, such as sending e-mail, are always Post forms. Some sites use Post forms for searches when the URL is ugly or long, which makes it difficult to bookmark the results of the search, but most of these sites also accept the same form submitted using the Get method.

• view passwords (Source)
  This Squarefree bookmarklet reveals what's behind the ***** in the password field on the current page. It's very useful when your browser has your password saved, but you don't remember what the password actually is.
• Print Friendly (Source)
  According to the PrintFriendly site,

  PrintFriendly cleans and formats web pages for perfect print experience. PrintFriendly removes ads, navigation and web page junk, so you save paper and ink when you print. It's free and easy to use. Perfect to use at home, the office, or whenever you need to print a web page.