It would be nice to have a plugin that puts something on the bottom of every post that allows people to press a little button for each of the various communities like Stumbleupon, technorati, MySpace, Digg, del.icio.us, google, yahoo! etc etc so that a person can add this to their favourites in that community.
You can see an example of this on the bottom of [url=http://ray.tomes.biz/]my main web page[/url] (this is as far as I got so far). I nicked this html code from several other sites and tried to streamline it. You can see that there are a couple of common things in each link but some differences also.
If nothing like this already exists then this should go to the requests for a plugin section I suppose.
I would be keen to have this optionally work for an individual post (to use the permalink in that case) or for an entire blog (use the minimal link for the blog). In the post case, the buttons should be within the post. For the blog, they might be in the side bar I guess.
This facility is of huge benefit in getting people reading your blog - which after all is presumably why we write them.