Thousands of WordPress plugins can be found in the WordPress community and every day brings some new ones. But, in spite of huge amount of plugins, not all of them are useful. Even more – some are very bad be written. This can cause errors in your WordPress installation or make harm to your site. To help you find right plugins, I made a list of those that I used before.

WP Cache

It’s useful for those who have low performance server or a high traffic site. It caches Worpress pages and puts them in a static file. So all further requests will be served directly from the file. There is no need to compile the whole PHP code and build the page.

WP eCommerce

Check out this plugin if you want to sell things on your blog. Use Ajax powered shopping cart, so it’s really simple to use it. Allows to setup your shop in a shortest term through the Admin panel.

Intouch Ajax contact form

Really useful thing for those who are tired of SPAM messages. Perfectly filters all these messages. Also can be used to trim thank you messages, email subject, and add addition form fields.

Secure and Accessible Contact Form

Similar to the previous one, this is a good contact form that has many good reviews. You could try it for yourself.

Sideblog

This is the easiest way to post your notes on the side bar. Allows you to specify the sideblog category, a number of entries for displaying and entries which are to be removed from RSS feeds.

WP PageNavi

Do you have a lot of posts? Then this plug-in is really good for you. It adds a better paging navigation to your WordPress site and allows your visitors to skip from page to page.

Sociable

Sociable allows your visitors to bookmark by adding a list of the social bookmarking sites at the end of your posts. Worked really well while using it.

Ajax Post Rating

Most of CSS galleries use this plugin. It appends a 5-star Ajax rating system to your pages and/or posts. Works perfectly!

Ajax Comment

Useful comment plugin, Checks if all the fields are filled correctly, helps to avoid comment duplication. Also protects from the flood.

Ajax Inline Comments

Allows your visitors to see Ajax live comment previews. Forget about the syntax errors in your comments!

Ajax Polls

Strongly recommended plugin. Adds an Ajax poll system to your site. Adjustable with a lot of features. Allows you to archive the polls. An Admin panel totally customizes its layout.

Gravatar 2 Plugin

Displays globally recognized avatars of commentators. Next performed Gravatar services run faster and support bigger avatars’ sizes.

Digg This

This plugin detects incoming links from Digg.com to your post and automatically display a link back to the digg post, for people to digg your story. Therewith, when a digg is recognized first time, it will notify the site’s admin by sending e-mail.

Subscribe to comment

Your commenters will be able to get email with any further comments to your blog by simply checking «Notify me of followup comments via e-mail» checkbox.

Admin Drop Down Menu

With this plugin your secondary menu will activate on mouseover. This saves a lot of time and clicks so plugin is strongly recommended for all the WordPress sites.

Adsense Deluxe

This is probably the best Adsense plugin available on the web. First, through the Admin options you simply define your ad code, then, when you insert a HTML snippet ("<!–adsense–>") into your post content, it will automatically put your ad code instead of snippet.

Search Everything

Adds some new features to the WordPress default search engine. Plugin will allow you to search everything in the database. Of course, there are some options, allowing you to set what to search.

Ajax Calendar

If your sidebar contains calendar, use this Ajax Calendar. Now your visitors will be able to browse through the calendar without refreshing the page.

Breadcrumb Navigation XT

Breadcrumb navigation is not very popular now, but if it’s what you want, this plug-in is perfect catch as it adds breadcrumb navigation to your site.

Google Sitemap Generator

It generates a XML compliant sitemap for search engines. Of course, most popular search engines support this plugin. This is probably the best choice for the search purposes.

Simple Recent Comments

Another strongly recommended plugin requires no activation. Can be installed as WordPress plugin or just included in your theme folder. Outputs a list of recent comments.

Simple Tags

As known of version 2.3, WordPress has a built-in tagging system. However, it has very limited features. Plugin gives you some new and useful features: manage tags (rename, delete, add…), type-ahead auto suggestion tags, edit mass tags, dynamic tag cloud colors, etc.

WP Mailing List

This is paid plugin which costs $14.99, but totally worth it. It will be really useful if you run some commerce shop on your WP. The best way to inform your subscribers about new products and updates is newsletter. All the plugin’s features can be seen here.

Category Tag Cloud

With this you can fake your categories into a tag cloud. Simply installed and arranged.

Paged Comments

It breaks your comments into a number of pages. This is really useful if you get a huge amount of comments on your blog.

flickrRSS

Your Flickr photos are easily displayed on your weblog with this plugin. It supports user, public and group photostreams. You can setup and arrange plugin through an options panel. It supports an image cache, located on your server.

Theme Switcher

With this plugin your readers can switch among installed themes. This plugin is useful if you offer WordPress theme and you want to let your users to preview the themes.