fsquared

The F2 Tumblr Widget displays recent posts from the provided tumblr blog.
It allows the user to select how many posts to display, to restrict which 
posts are shown by type and tag, and to render the posts as either a list 
or a slideshow.
Posts can be displayed in full, as title only, or with an excerpt. Photo, 
video and audio posts will have the media displayed when the display type 
is not ‘title only’.
The audio player in posts can now be automatically resized to match the 
selected media width – this is enabled by default, but can be deselected 
in the widget setup.

F2 Tumblr Widget

This widget displays recent posts from a tumblr blog.

jeffikus

Create a tumblr style blog using this plugin. Simply install the plugin, add the easy to use tags to your theme, and your blog will be transformed into a Tumblr-style blog. Create posts direct from the WordPress dashboard, your iPhone, or the familiar WordPress interface.

WooTumblog

Create a tumblr style blog using this plugin.

F2 Tumblr Widget vs WooTumblog