These are some nifty things I’ve learned about Tumblr that I thought I’d share because you never know who doesn’t already know these things, I’ve learned.

First off I’ll let you all know that I am using Firefox 4.0.1 and I do not have any special extensions for Tumblr except Tumblr Savior which is hardly used. I do however have NoScripts, Ghostery, Adblock Plus, and do not accept cookies except from specially designated sites.

1. The Magic of Tagging
   Turns out the tagging and search system is actually a really borky feature. So just because you tag something doesn’t mean it’s going to show up on dashboard search, however, tagging it in as many ways as you can possibly think of certainly helps. Anyway, personally I use tags more for ease of browsing my posts than for gaining attention. By adding /tagged/[wordhere] to the end of my page’s URL I can easily organize my posts, provided I’ve tagged them (as you can see by the link selection on my main page’s side bar). 
2. Mass-Editor is Not For Editing Posts
   That being said, the Mass Post Editor actually does not provide the ability to edit your posts, at least not for me. Instead, it’s more for editing (adding and removing) their tags and for finding your posts by month and year. 
3. Reblog Options
   Did you know you had options when you reblog? It’s right at the top, where it says “Reblog Photo(set)/Link/Video/Audio/Quote/Text Post”. Right next to it is a little grey button that says “as …” - if you click on it you will see the options you can switch through. This is great for when Tumblr tries to turn Text Posts into Links. Be careful, though, as some options don’t translate through well, and you can’t reverse them (you’ll have to go back!). 
4. Post Options
   There are also several options for your posting pleasure, located on the side. I’m sure everyone’s aware of the tag field, but above it is a Source field, a field where you can change the post date, a drop-down box with nifty options such as saving as draft, queuing, or posting privately, and of course a Post To drop-down box for where the post will be posted (if you have multiple blogs, that is). And below the tag field, we have a way to set a custom URL (as opposed to Tumblr just taking the first few words for the URL), a Send to Twitter option (if you’ve connected accounts) along with the ability to edit what the tweet will say, and options about people’s replies and answers. You can toggle the appearance of the “Let People Answer” option by adding a question mark at the end of your post.
   If you are posting a photo you have the ability to set a click-through link, which will only work on the post’s page, not in someone’s dashboard.
5. Browse Someone’s Likes!
   http://www.tumblr.com/liked/by/[usernamehere]
6. Tumblr Copies Everything As It Appears From Where It Was Copied
   So if you have a post with specially coded links in it that contain your personal information (such as links from emails that auto-fill your info into certain fields), please remember to replace those links or break them. Tumblr will transfer over bold, italics, links, and so on, the only exception seemingly being font size.
7. Read More Button Won’t Work? Use the HTML Editor!
   When using Read More, always remember to hit Preview before Create Post to make sure it actually works - because a lot of the time it doesn’t want to. In the case that it doesn’t, usually you can fix this by going into the HTML Editor and copying the Read More HTML code, then directly pasting it beneath the Read More code already there. This usually corrects the error, but not always!

That’s about all I’ve got to say.