Tumbleroo for Tumblr This is the only iPad app I've been that allows you to post new updates. All the others seem to only have reblog/like features (which don't get me wrong that's majority of Tumblr). Tumbleroo will easily let you reblog posts from others you are following or create new posts on tumblr. You can schedule posts for later or post immediately from the app. Also what's great is if you have multiple tumblr sites under one login you can view and post to each one.

TumbLiking -Tumblr client- This is a great app for quickly viewing posts from people you follow. You have the option to view only photo posts or all types. I like to set mine to Photo only and use the slideshow feature to "Play" the photos. If one I like pops up I can pause it and easily hit "Like" or "Reblog" viewing photos in a slideshow format on the iPad screen is much more fun that flipping through photos on the computer.

TumTum for Tumblr One of the cool features of this app is you can quickly see which posts are mot popular by viewing the number of comments/likes/interactions each post has. The thumbnails are pretty small but being able to see the number of comments is a quick way to view only the most popular posts. Once you click on a thumbnail you can see the image bigger (still not full screen though) and very there Like or Reblog it. Pretty cool app, especially since it's free.

Tumbletail lite for Tumblr This app, also free, provides an interesting combination of grid and full size image preview. It works best in landscape view with the left 3rd of the screen showing thumbnails and the right showing larger view. With each photo you have the option to Like, Reblog, Save to Camera Roll (a feature I haven't seen in the others), or Tweet a particular photo.