We have talked about the various ways through which you can post to Tumblr; through the desktop, mobiles or browsers. Putting stuff on tumblr is so easy, that you can also do it through email and a phone. However, all that aside, right now I have two Google Chrome extensions to tell you about.
Tumblr Dashboard: the Tumblr Dashboard extension for Google Chrome brings together the Tumblr interface for iPhone and the Tumblr bookmarklet for the web. If you need to see your dashboard quickly, see it through the iPhone interface. If you need to post content, you get the bookmarklet interface. In the dashboard mode, clicking on a post shows you details such as number of notes and options like the ability to like and reblog a post. If you click on a picture thumbnail, the extension will enlarge it for you.
Share on Tumblr: If you just want a quick and easy way to post content, the Share on Tumblr extension might be what you are looking for. It gives you the same features of the Tumblr bookmarklet, in fact, all the extension does is load the bookmarklet in a frame. You can choose this option if you like a fixed placement for the frame and want an interface the feels native to the browser, as compared the bookmarklet.