One problem with blogs that recommend all kids of tips, software, browser add-ons, web applications is that very few will be actually used by someone. I tried to only link to great software, useful Firefox extensions and Greasemonkey scripts, difficult-to-find Google tips, but quality is subjective.
I still view the latest videos from my YouTube subscriptions inside Google Reader, I log into Google using an alternate username, I upload files using drag and drop and share blog posts from the web to my Google Reader link blog, Google Cache is still useful to navigate inside a web site when it's inaccessible and linking to web pages using Google AJAX Search is very convenient. Gmail's built-in labels are great for creating filters or complex queries, wildcards are one of the ways I extract facts from Google search, while Interclue is a smart and unobtrusive link previewer.
Which tips that you first read here are still valuable for you?