I've been running version 2.3 of WordPress for a couple weeks now and I'm getting more accustomed to using tags with my posts. One thing that struck me about the default handling of tags is that, while free form, it's a bit unwieldy for long term use. For example, you have to remember what you named various tags ("did I use web or internet?"). The [Simple Tags] plugin gets rid of most of the problems associated with tagging and makes it an absolute joy to use – I've been using for editing my posts for a few days now and I love it.
Installation of the plugin is as simple as you can get: upload to your WordPress plugins directory and then activate from the admin area. Done! Configuration is pretty simple as well and you'll probably find you don't need to adjust anything from the defaults.
Actually using the plugin is, of course, simple as well. When you type into the Tags field below the post editor an auto-suggest box will be brought up with tags that you've already added to previous posts, which lets you quickly and easily make sure you're using the same tags across different posts. If you save the post and then edit it you are also presented with a list of suggested tags that you can just click on to add to the list of tags. These things fit in with the existing system very well and don't get in your way.
Simple Tags also provides some other handy features, such as managing the tags for you blog and allowing mass editing of the tags for your posts. Mass editing is excellent when converting to a tagged blog as you can change the tags for numerous posts all on one page, complete with the auto-suggest feature found in the post editor.
If you are using the tagging feature of WordPress 2.3 I highly recommend using this plugin – it will make your life a whole lot easier.