How many times did you post something in a blog or in a forum, but felt you need to add a link that explains a concept or a link to the homepage of a product? Laurence Gonsalves from Google used Google AJAX Search to create a bookmarklet that performs a search for the selected text from a form and lets you insert a link to one of the top search results for that query.
The bookmarklet seems to work only in Firefox and Opera. You just have to drag the link to your bookmarks toolbar. (Make sure the bookmarks toolbar is visible in your browser. You can make it visible if you go to View/Toolbars and enable Bookmarks Toolbar in Firefox or Personal Bar in Opera. Alternatively, you can just bookmark the link.)
Then everytime you need to quickly add a link in a textarea, type a text that will become both the query and the anchor text, select it, click on "Linkify" in your toolbar and then click on "Create a link" in the Google AJAX search sidebar.
You can use it when you post a comment to a blog, when you write a blog post or in other situations when you write in a textarea. Unfortunately it doesn't work with Gmail or Google Docs & Spreadsheets.