There are many plugins that allows you to show your blog comments in various styles. Some allows you to display comments with avatars, some displays top commenters, featured comments etc etc. But there are very few plugins or might be this is the second one that allows you show your WordPress site’s Trackbacks and Pingbacks as sidebar widget.
So if you are looking for such kind of plugin then install and activate Trackback and Pingback Widget. After activation visit Dashboard -> Appearance -> Widgets page and drag its widget to sidebar or any other widget area of your theme. It provides you option for displaying trackback date, select an order and number of trackbacks to show.
Alternatively, you can try using Recent Trackbacks & Pingbacks Sidebar Widget, it provides you few more options like you can add trackback link relationship i.e. ‘rel=nofollow’ attribute to your links, you can define number of characters to show in the excerpt you are displaying with link and also you can exclude your own (internal) pingbacks.