jQuery Forum

use one of the various insertion methods in the manipulation section og jQuery API
http://api.jquery.com/category/manipulation/

There are examples and well documented descriptions for each method. Pick the one that best suits your page layout

would look at append() or prepend() as starting point

as for smooth display look at effects section of API
http://api.jquery.com/category/effects/

fadeIn() or slideDown() good start points

So theoretically if I click a link on my webpage say to activate or deactivate a user, I could use append() to add a <div> to the page containing controls?

yes

That's great! Is there any way to limit how many can be added?

sure...how it gets managed depends on what criteria would control the limits

I'm thinking of just limiting it to one <div>