The G-bookmarks extension offers a great way to access the Google Bookmarks right in an active tab. You find your bookmarks quickly by selecting one or several labels. G-bookmarks tells you labels crossing as you select them with a blue color highlighting.
Moofmarks lets you search and access your Pinboard bookmarks without actually going to the site. Press Command-K (or your own shortcut) on any page to show a popup search bar. As you type, Moofmarks will update a list of bookmarks that match what you type in name, description, or tags. Highlight the one you want and press Enter to open it.
Licorize is the official Safari Extension for Licorize.com, which allows you to share bookmarked sites, to-dos, and to collaborate on group projects online. The extension allows you to bookmark URLs, annotate them, or share them with a team.
This extension allows you to navigate your Instapaper bookmarks and folders, as well as edit, archive, and perform other functions from your keyboard. You can send content to Delibar, Evernote and more.
This extension adds a toolbar and buttons for Pinboard, a bookmarking service. You can add the current page as a bookmark or to read later, as well as annotate. You can view your own Pinboard, and see unread, recent or popular posts.
This extension works with your Diig account and allows you to save webpages to read later on your iPhone or iPad, or share pages with Twitter, Facebook, or email. You can also annotate webpages with highlights, comments, or sticky notes.
This extension allows you to easily capture web content to save to your Memonic account. You can save URLs or just selections of content to read later, access it from your iPhone or iPad, or share it on Facebook and Twitter.
Quiet Read from bambooapps lets you drag links to a menu bar item, so you can visit them later. This extension works with the Quiet Read desktop application and saves your links to it for you.
InstapaperIt lets you send links to articles to your Instapaper account. You can choose one of two ways to do this: Click a link while holding down a modifier key or select the contextual menu item.
Papers is an application that lets you view, browse, and search your articles and PDF documents in an iTunes-style interface. The Open in Papers extension adds a handy toolbar button to Safari so you can open the current web page in Papers. It acts as a replacement for the Papers bookmarklet.
Procrastinate is a Safari extension that integrates with popular websites such as Instapaper, Read it Later, Pinboard, and Delicious. Procrastinate features a customizable toolbar and a contextual menu item that allows you to send any page or link to your reading list or bookmark service — without interfering with your browsing.
One click on the toolbar button and the URL you are currently viewing will be saved to your Little Bookmark Box application.