Here’s a question that I wanted to share that was posted in one of my LinkedIn groups:
What plugins you find yourself using on every site you design? Name your top five and tell me why you find them so necessary.

All sites are unique, but I would recommend the following five as the essential plugins for almost every WordPress install.

1. All in one SEO pack

It’s pretty obvious what this plugin does. SEO is one of the most important things you can do to your site. This plugins gives you a great start.

2. Google XML Sitemaps

This helps Google find and index every page on your site. Once you install and create, you’ll need to create a Google Webmaster account and add your sitemap. google.com/webmasters/tools/

3. Gravity Forms

This plugin is very well done and one of my favorites to use , but it’s not free. Great for contact forms, newsletter signup, consumer feedback and anything else you can think of.

4. Disqus

If you have comments on your site, this is the best way to manage comments.

5. Widget Logic

This plugin is a little geeky, but this is the best solution for controlling your widgets. For example, if you want a Google map widget to just appear on your contact page, Widget Logic lets you do this, otherwise with most themes, that map widget will be on every page.

5. WP-PageNavi

This lightweight plugin replace the “older posts” links with “Page 1 2 3 4 next >>” style navigation. Better for SEO, better user experience and makes you site look less “bloggy”.

Other Notes:

Google Analytics – I recommend everyone use Google Anatytics and there are many plugins for integrating this code, but if you know any HTML or use a built theme you wont need them.

As I mentioned on the all in one SEO plugin, the most important thing you can do is to optimize your site for search engine. Yoast has a great step by step post on doing this: http://yoast.com/articles/wordpress-seo/