Displaying most popular posts of your blogspot blog on your blog is a great idea. First time users will be able to get what your best content is and Google will do a cyclic and chain reaction for indexing your already indexed posts and give more value to it as it will be on all pages. Being on all pages mean more linking to it and hence its kind of promoting your popular content to search engines and users.
Tip – Placing recent posts or any other link on sidebar creates a digg like effect on your links. As they remain on your each and every page, Google will have to ultimately crawl them. Thus you should always care for the things you put in sidebar.
I found today a widget to display most popular posts on your sidebar in your blogspot blog automatically. Here is how to do so.
Just go to http://draft.blogger.com and add a gadget which is the very first as shown in figure.