Some selected WP Plugins that I find useful.
Extending WordPress: on WordPress.org: plugins, themes, mobile, ideas
Jetpack by WordPress.com: Supercharge your WordPress site with powerful features previously only available to WordPress.com users.
Tumblr Importer: Import posts from a Tumblr blog.
Awesome Flickr Gallery: import Flickr sets/groups into Lightbox slideshow.
Akismet, protect yourself from spam.
Fast Secure Contact Form: This free contact form software lets your visitors send you a quick E-mail message. Blocks all common spammer tactics. Has a multi-form feature, optional extra fields, and an option to redirect visitors to any URL after the message is sent. Super customizable.
Regenerate Thumbnails: allows you to regenerate the thumbnails for all of your image attachments. This is very handy if you’ve changed any of your thumbnail dimensions (via Settings -> Media) after previously uploading images.
Viper007Bond Plugins on WordPress: by the author or regenerate thumbnails