I've just released Data::UUID::Base64URLSafe:
Data::UUID creates wonderful Globally/Universally Unique Identifiers (GUIDs/UUIDs). This module is a subclass of that module which adds a method to get a URL-safe Base64-encoded version of the UUID using MIME::Base64::URLSafe. What that means is that you can get a 22-character UUID string which you can use safely in URLs.
Of course, only afterwards do I notice Data::GUID::URLSafe. What is the point of a Globally/Universally Unique Identifier if we don't have a unique name for the concept, eh?