We've just pushed out a large amount of improvements to the Skill Calculators! Overall, your experience should be very similar but the calculators have been rewritten from scratch. This allows us a lot more control over the calculators and opens the door to implement new features, such as the brand new category support!
Check out any of our OSRS skill calculators and you should now find an option to view a particular type of action/item. This should help with some of our bigger calculators, such as the Smithing Skill Calculator - allowing you to view only the type of metal you'll be working with, etc.
As a side note, the work done behind the scenes that allowed these improvements spills over into every area of the website. A lot of upgrades have been applied and I'm in the process of rewriting the rest of our popular calculators. Keep an eye open for these new improvements!
As always, reach out if you notice any bugs, incorrect/missing content, or have a suggestion. Once again I want to thank everyone for the tremendous support you've shown me with this project. Let your friends know about the site as well!