Speaking of feature creep, web resources are one of the few system-level data items that can sort of build-up over time, if not properly maintained. Again, this happens because of a change in business direction, a rewrite of functionality, etc.
Dynamics CRM has a built-in dependency checker so you can see if your development resources are being used elsewhere in the system. While working with a solution, any time you see the Show Dependencies button, you can perform this operation.
In the case of a web resource, all you have to do is highlight the web resource and click the Show Dependencies button:
If there are dependencies, they will be shown in the dialog below:
The only time I have seen this feature not work was in Dynamics CRM 2011 where JScript web resources associated with a Ribbon Button were not properly identified. I think that was corrected in a later version.