One of the most common questions I see in the forums is, "Is there a component/module/mambot/plugin that does (insert your function of choice here)?" Whenever I see a question like that, I head over to the Joomla! Extensions Directory (JED), perform a quick search, and find a list of components that either meet the person's need, or come really close to what the person wants. At the time I am writing this, the JED lists 947 Joomla! extensions.

My point is, if you ever find yourself needing a specific function, head over to the JED and do a quick search. Chances are, if you can't find it there, you can't find it anywhere.