These components are available as a flex library project from github.
Documentation is available online here.
CheckBoxGroup is a Flex 4/Spark component. Specifically, it is a subclass of DataGroup with a few bits of List (like labelField/labelFunction) for convenience.
CheckBoxGroup takes a dataProvider, like DataGroup. It will display a list of CheckBox controls using the label from the user-defined labelField or labelFunction.
On top of DataGroup, the API is fairly simple. A selectedItems property supports databinding and is updateable.
This component supports virtualized layout and has been tested with 10,000 objects.
XHTMLTableGrid is a Flex 3/4-compatible component. It takes a XHTML table and turns it into a Grid.
This is currently in early development and does not support rowspan/colspan although adding that will be easy. No styles are supported at this time.