One of the nicest things about modern browsers is that they can "remember" the text strings you type into certain kinds of Web-based forms. On the downside, they also remember your mistakes and typos, and sometimes this results in incorrect values being reused. My mission over the weekend: Find a way to get rid of the old values, without nuking the whole cache.

First, it's important to understand how the data is memorized and reused. Usually this is done by linking an input field label with the input field data--whatever you type into a field called "e-mail" is stored separately from whatever you type into a field called "email"--and when you next go to fill out a form, the software will call up the appropriate input value based on the label it encounters. This is why some values only show up in some places--maybe you used the wrong e-mail address for a form that uses one type of label, and it only appears infrequently.

There doesn't appear to be a prepackaged way to edit these stored label:value pairs directly, and the only prebuilt tools I could find would either disable the autocompletion code or purge the database entirely.

However, there's a way to delete single entries within Firefox itself, which can have the same effect. Specifically, whenever you start typing into a field, Firefox will display a drop-down list of the eligible stored values that match the field label and the letters you've typed. When this list appears, move your mouse to highlight the entry you want to delete, hold down the shift key, and then tap your delete key. The entry should be purged. Go ahead and type in the correct value and when the form is processed, Firefox will store the new value in its cache.