Option for grouping bookmarks by folders

[aekin]

When the number of bookmarks is large, it is difficult to navigate through a single large bookmark list. (One needs to scroll down the list)

An option for grouping them in a folder structure would very useful to be able to organise the list. (Similar to web browsers like IE or FF)

I think, even a folder structure of a finite number of levels of depth (eg:2-3) would be fine for most users.