Ajaxify adds some great new features for your blogging pleasure.
The two notable additions:
EnhancedEntryEditing - Adds the ability to easily resize textareas and a powerful WYSIWYG editor so you never have to worry about HTML ever again.
SearchSuggestions - Adds a search suggestion feature to the Quicksearch box.
The second is for those of you that are interested in skinning your site but are really not interested in messing too much with the manual editing of the CSS.