bookmarklets are smart links: instead of pointing to pages, it runs simple scripts. Used wisely, it’s a huge timesaver.
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to use it, simply drag the titles to your bookmarks bar.

EMAIL

Composes an email with the info of the page you’re currently browsing: subject is the page title, body is page title + link. A godsend.
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It breaks if the title uses ampersand.

TWITTER

Same as above, but as a popup to your twitter post page. Link is minified automatically. You gotta be logged in tho.

MOODBOARD

Opens a query popup, you type your term and it builds a spezify moodboard for you. Good for quick inspiration needs or if you wanna check art/fashion/design terms.

LATER

Saves the page to instapaper. If you want, you can even install the iphone app to read on your commute: no interruptions. You need to setup an account tho.

READABILITY

Cleans cluttered article pages: just the content, please.

SELECTOR

That’s for webdesigners: It allows you to click on page elements and give you info about it (classes, etc). Good for reverse engineering.
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PS: Safari has a nifty keyboard shortcut: command/control + 1 opens the first link, command/control + 2 opens the second, etc. If you keep same order it makes life even easier.
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Firefox works differently: you can setup keywords under link properties (option/right-click), and if you type it on the address bar and hit enter, it opens the link.