Recently Popular records hits to any post or page on your site by any user who isn't logged in, then allows you to display the most active ones for your defined time period on your sidebar.
Redirect Old Slugs plugin will notice when you change the slug of a published post or page, and it will save the old slug as a custom field (the key is old_slug). Now, when someone tries to go to the old post, the plugin will say “hey, that looks like one of the old slugs I saved, let me redirect you to the new location.”
SEO Friendly Images automatically updates all images with proper ALT and TITLE attributes. If your images do not have ALT and TITLE already set, SEO Friendly Images will add them according the options you set. Additionally this makes the post W3C/xHTML valid as well.
Pathless Category Permalinks remove the /category/ base directory that WordPress adds to category links. It’ll also go beyond that and automatically 301 redirect the old /category/ links to the new, pathless category link.