It would be nice being able to tag any word/phrase stored in the word list. I mean something like labels in GMail or tags in Anki, which are optional of course, but very powerful and useful as well.

Some people might just like to tag words as "verb", "noun" etc.; some others might like to assign more personal tags as "fun", "love", "idiomatic" etc.

This would provide an alternative method for researching group of words in the word list and it would allow to use some flash card sessions only for them.