After years grappling with Movable Type for our gaming site blog, I’ve recently come to really embrace WordPress’s simplicity and extensibility. One of the things that makes it so great these days is the ease with which you can add and update plug-ins used to improve the features of your blog. In most cases, you can just click a link to install or update a plug-in (no more FTPing files!).

There are thousands of plug-ins to choose from, so from time to time I’ll call out the ones I have found indispensible or at least highly valuable, plus the occasional one I’ll suggest with reservations (and helpful tips to save you the trouble we had implementing it). Here are some of my favorites so far:

WPtouch iPhone Theme. I found this theme when browsing a friend’s blog and immediately installed it for our own. It greatly speeds up load times and improves readability for iPhone visitors, who have the option to turn it off if they prefer your default view. The way this makes your site look like an iPhone app is pretty compelling (see picture at right).

Add to Any: Share/Bookmark/Email Button. If you write something worth sharing, you want it to be as easy as possible for your site visitors to do just that. You can select which social networking/sharing mechanisms are displayed by default. Hovering over the Share or E-mail This Post link opens up the full list, which is constantly expanding (see icons and link at bottom of this post).

WP to Twitter. This highly configurable plug-in automatically tweets your blog posts. We use this only for new posts, so any updates/edits do not result in an unwelcome Twitter flood. URLs are automatically shortened using the Cli.gs service, though we had some problems until we created and entered a Cli.gs API key.

Simple Tags. If you don’t want to spend a lot of time adding tags (aka keywords) to your posts, this plug-in can help, although it can be tricky to get working. First, you have to add at least one tag to a post before it will function at all (you’ll get a “Javascript must be enabled” message but that’s probably not your problem). The autotagging feature only pulls tags you have entered previously and applies them, where relevant, to existing posts. Once it’s up and working, use tag suggestions to find common keywords in your articles and apply them quickly. After you have a decent set of local tags, the auto-tag feature can help you quickly generate tags for older posts that don’t have them.

Have you had different (better, worse?) experiences with these plug-ins? Have a favorite plug-in that nobody loves but you? Let us know!