in my experience, most of the best widgets can be found in paid themes. you have to buy the (complete) theme in order to access the widgets. sometimes this is not even necessary but they are not easy to find as they disguise the package name with a reference to a particular theme. others are sold in full iwidget packages, and not individually, which makes the process even harder.
but there are sites out there that have good stuff even if its not freeware they can help you find them in cydia. a few that come to mind are deviantart, dbar, modmyi...
directly searching for iwidgets in cydia is a fruitless effort - you will come across lots of junk or stuff from when Jefferson was president.