Plugins for jQuery:

checkbox manipulation - working with checkboxes
dialogIframe - Opens links in an iframe in a jQuery UI Dialog box
dialogImage - Opens images in a jQuery UI Dialog box
fix Q tags - wrap q tags with proper quotes in Internet Explorer
focus fields - add an outline and background to text inputs when they are given focus
jQIR - replace text with images
newsticker - a news ticker for sequentially showing each item in a list
numeric - allow only numbers to be typed into a text box
preload images - preload any images that you may use in the future (e.g. for image rollovers)
select box manipulation - add/remove options in select boxes as well as sort them
time picker - display a list of times when you click on an input