tInput is a textarea and input manager plugin for jQuery. It is lightweight and works with older versions of jQuery as well (has less than 5kb minified and works with jquery 1.2+)
It works in all major browsers, including Internet Explorer 6.0

Features:

• dynamically resize any textarea once text enters the “scroll area”
• add any type of image borders to any element on the page (like rounded corners) easily. Just specify a folder path and name your files correctly and the rest is automated
• set a min-height and a max-height that a textarea can have while resizing. Add a typicall scroll after that
• make any textarea look and perform like the one of Facebook with the setStyle attribute.
• add a focus and a blur effect to the fields
• restrict the characters than can be inserted to the field. i.e: only numerical, or only lowercase, or any type of RegEx you can think of
• possibility to disable certain special characters within a field. i.e: disable the ENTER key, or the ALT key, etc
• possibility to set the writing cursor to a certain position within a field
• add a maxlength value to any input, including textareas
• attach a dynamical “characters remaining” counter
• attach a dynamical progress bar that displays the number of characters used
• set default text for fields that are empty
• set a custom style for fields that are empty
• set a custom style for the wrapper of the fields that are empty