Simple & Effective Rated 4 out of 5 stars
I use MyWords at least a few times every Firefox session, often far more -- I use it for my public & temporary email addresses, standard login names for starting new accounts, and my OpenID address. I really like how easy it is to add new entries.
There are two things that could really improve MyWords... One is if we could nest folders in the context-menu, as that would make a lot of entries easier to work with. The other would be for the configuration window capable of using small/single-line text areas or even just labels, so we might see all of our entries (or their labels) at once.