I have a sidebar filtering system and I have data that I want to filter on that looks like this:

FilterSection (not selectable)

• Category1 (select all action link, or checkbox that selects all subcategories)
  • Subcategory1
  • Subcategory2
  • Subcategory3
• Category2 (select all action link, or checkbox that selects all subcategories)
  • Subcategory1
  • Subcategory2
  • Subcategory3

I also have a section that displays the currently selected filters and allows you to clear an entire section of selected filters (FilterSelection) , or clear individual filters (Category/Subcategory in this case)

Is there a UX pattern that best suits this kind of filtering?

I don't want to use nested checkboxes, because having multiple levels of checkboxes seems wrong and not a great user experience (if you're a Microsoft power-user, you may disagree). I've also toyed with the idea of having a "Select All" action link that selects an entire set of Subcategories, but there has to be a better way to represent this.