Create automatic excerpts in WordPress, with Auto Limit Posts plugin
You may find annoying for your visitors to have full versions of your posts gathered one after another in your front and archive pages of your blog. Auto Limit Posts lets you cut down your posts automatically in Home, Categories, Archive and Search pages, without having to provide the necessary WordPress tag each time you compose a post.
It will also let you format the reference link it produces, writing yourself the exact text leading to the main post page (e.g. “Read More”, etc), even use simple CSS to add or remove link decoration or border, change color, etc., through the plugin’s settings at your admin section, or using the #alpr tag in your style sheet.
Auto Limit Posts will not include the rel=nofollow tag in the reference link to the address of the full-text version of your post, a tag that may damage the popularity of your posts.
The plugin is absolutely free.