Until I started blogging, I didn't realise that you could add lots of bells and whistles (aka 'widgets') to your blog that do everything from analyse hits from visitors to allow people to instant message the blogger.
I prefer to keep things simple. However, there is one feature I decided I needed to add to my Blogger blog: trackback. When I refer to someone else's blog post I'd like them to know about it, without me having to post a comment on their blog saying so. Similarly, if others are referencing my post, I'd like to know about it. Trackbacks are the glue that allow readers to follow a topic among multiple blogs. They typically appear as comments on a blog post containing a link to the referencing blog post, as well as an excerpt from the text.
Blogger blogs don't provide this feature, although they do have a related feature which in some ways is more powerful. Since Blogger is owned by Google, it is able to identify any websites that contain a link to a particular blog post and list them under "Links to this post". However, it's not clear whether the link is from a blog, nor is there any summary text included. Trackbacks are active acknowledgements by one blog of its link to another; the Google backlinks are passively harvested from the web.
Outgoing trackbacks can be enabled using the Greasemonkey script by Stephen Weber. When you are creating the blog post, there is a box for entering trackback URLs (typically found at the end of a blog post). To enable incoming trackbacks is slightly more difficult, as it requires the help of a third-party site HaloScan to manage the trackbacks. First you need to create an account. Then you need to manually edit your blog template as described on the HaloScan Forum (your mileage may vary). This adds trackback URLs to the end of your own blog posts allowing others to reference your posts.
Can anyone suggest any other 'essential' blog widgets?