A license to use Gravity Forms on a single site is a reasonable $39/year; pricier tiers come with additional sites and functionality (such as PayPal and MailChimp integration). The plugin doesn't cease functioning at the end of the year, but updates and support become unavailable. Since security flaws or WordPress updates can break a plugin, it's risky to let a Gravity Forms license expire, so users are best off renewing.
Jetpack is an official product of Automattic, the company behind WordPress.com. Designed to give self-hosted WordPress users those features otherwise exclusive to the WordPress.com hosting service, Jetpack's functionality is not limited to a single feature. Instead, it currently offers 13 different tools, each of which can be enabled or disabled.
JetpackClick to view larger image.
A few features are must-have, warranting installing the entire Jetpack package: crafting and embedding "contact us" and other custom forms, letting readers subscribe to receive notification of new comments and posts, site traffic analytics, and improved integration and sharing with Facebook and Twitter.
Some features are conveniences. For example, for bloggers who don't want to copy and paste embed code from external sites, Jetpack automates the embedding of media from YouTube, Slideshare.net, Google Maps and more, simply by pasting the URL to the original media.
And some functions are extremely focused: Bloggers who need to post complex mathematical equations can use the LaTeX markup language, courtesy Jetpack.
Jetpack itself is free; according to the website, some individual features may require payment in the future. Whether you need one feature or all 13 (and there are more presently labeled only as "Coming soon"), Jetpack has become an essential component of any WordPress installation.
WordPress 3.0 added custom navigational menus that can be dragged and dropped into various themes -- but only if the theme is designed to support that feature. Otherwise, you may be stuck with a long and confusing list of links in your navbar.