While not specifically designed for use in Blogger blogs, Google's "Feeds in Tabs" gadget is awesome, and wholly compatible with Blogger templates.
Read up to four Atom or RSS feeds from within a single gadget using tabs. Feed titles and descriptions are optionally included and can be turned off. Customize the font-size and text for tab titles. Fetch 3-12 entries per feed including summaries if available.
Screenshot


Installation

Add the title and URL of each feed you would like to include in the gadget. You could, for example, add the following:
  • Your Blogger posts feed for recent posts
  • Your Blogger comments feed for recent comments
  • The URL of the RSS feed for your Twitter updates
  • Any important blogs you follow or are affiliated with
The font size of the headings may be customized for aesthetic purposes, and to ensure your titles fit within the available space.

Further choices include:
  • Display descriptions (summaries of entries in each feed)
  • Length of summaries (if chosen)
  • Number of entries for the feeds
  • Render HTML (this enables links and images to be displayed)
  • Show timestamp (date of each entry).
Developed by Google.