I have searched up and down the internet for a jQuery widget that does something similar to what is used on mint.com for transactions. Is there any such widget available?
For those of you who do not use mint.com, it is a drop down menu that you can click in and type in. As you type, it searches for things in a database, and gives you a few options based on what you typed in, as shown here:

If you really have no idea what you want to type in, you can click the dropdown for a categorized list, as per here:

Does anyone know of a jQuery UX/UI widget that has similar functionality?
http://jqueryui.com/demos/autocomplete/
You can have it use ajax to fetch DB results as well .. it took a little bit of tweaking to get it to work exactly how I wanted, but it’s very flexible and it didn’t take me all that long. It can definitely be done.