* angular filter "find" fixed : if 1st param is an array, an array with the matching (2nd parameter property) elements will be returned.

* angular filter "map" (:property?:default?) added : map can map a property of the right side array items to a object from another array.
the map filter can take 2 arguments. 1st argument is expected to be the property to return from the item.
2nd argument can be a default value return in case the given item doesnt have the property.
if no default argument is given items doesnt having the property will be filtered out.

example usage:
data = [ { id : 0, category : 'a'}, { id : 0, name : 'b'}];
...
<div ng-repeat="c in data | map:'category'">{{c}}</div>
-> <div>a</div>
   <div>b</div>

more complex example:
categories  = [ { id : 'a', caption : 'Alpha'}, { id : 'b', caption : 'Beta'}];
data 		= [ { id : 0, category : 'a'}, { id : 0, name : 'b'}];
...
<div ng-repeat="category in categories | find( data | map:'category')">{{category.caption}}</div>
-> <div>Alpha</div>
   <div>Beta</div>