The plugins below can go a long way toward preventing your visitors from ever seeing a 404 page. These plugins are all free and range from plugins that automatically redirect your visitors to ones that simply log 404 errors.
Click on the linked headings to download the following plugins for WordPress:
- 404 Notifier
This plugin from Alex King will help notify you of any 404 errors coming up on your site. It’s a very useful plugin to use if you’re changing your permalink structure or otherwise moving things around and are worried you may have missed some things and don’t want to risk broken URLs. - Smart 404
The Smart 404 plugin helps eliminate 404 pages automatically. If a visitor reaches a page that will return a 404 error, this plugin searches the requested URL to see if there’s some other post that likely matches. If there’s more than one potential match, it can return a list of possible links. It goes a long way to help remedy a high bounce rate caused by 404 errors. - Useful 404s
A plugin that creates more useful 404 pages, including a number of things mentioned in the A List Apart article “A More Useful 404“. - The Free 404 Plugin
This plugin creates a customized 404 page that includes related posts to whatever keywords appear in the requested URL. - JH 404 Logger
This plugin adds a dashboard widget that displays recent 404 errors. It’s a great, unintrusive way to see if your site is returning errors. - WP 404 Images Fix
This plugin lets you replace images returning a 404 error with a default image of your choosing. You also have the option to add a class to the img tag or hide the image entirely if it’s missing. - Dunstan-style Error Page
This plugin can be used to create a custom error page similar to the one used on Dunstan Orchard’s 1976design.com/blog. The custom page it creates is immensely useful to users, displaying the last five blog posts, a search box, and the option to report the error, among other options. - Permalinks Moved Permanently
This plugin is helpful if you change the permalink structure of your blog and don’t want to lose out on incoming links going to your old pages. In addition to redirecting the visitor to the new link, it also generates a “301 Moved Permanently” error so that visitors are automatically redirected in the future (along with search engine spiders). - Redirection
This plugin monitors 404 errors and lets you map them to 301 redirects. It also allows you to set a custom redirection that lets you pass a URL through to a different page, file or website. And it creates a full log of all redirections. It can be used to redirect both nonexistent pages and ones that exist and it can be set to redirect based on login status or other parameters.
Once you check this box you'll see the configuration options for your ads. You can then select how often you would like ads to be shown after your posts.
For example, if you want ads to be displayed after every post, select "1" from the drop-down menu. (Please note that AdSense policies limits you to a total of 3 ad units per page and Blogger will automatically prevent you from going over this limit.) You can then select your ad format and colors. Once you have finished configuring your ads, click on the orange "Save Changes" button in the bottom right corner. 
Once you've enable this Labs feature, then you can add the posting gadget by simpling entering its URL into the Gadget tab in your Settings. Here's the URL: 
grown slowly over -5-6 months), link bait tools (permanent homepage mashup (web app)/lead capture tool), posts comments on related blogs regularly and an automated ping service that will notify social engines and Google when content is updated for increased crawls. The combination of those tools over a 5-6 month campaign should result in a healthy backlink number of at least 1000 new quality backlinks. You want to grow backlinks conservatively but consistently to get the most out of their SEO value.
9. Propeller – PR7 – 322,000 links
