What are you looking for in a numismatic reference site?

I've been spending a bit of time over the past few days making tweaks to the So-Called Dollars website. Among other things, I added:

• A site-wide search (near the top of the home page) so that someone would be able to find a listing if they don't know the HK number in advance
• A way to link to a specific listing if you know that you want one entry on a large page (example: http://www.so-calleddollars.com/Events/New_York_Worlds_Fair.html#HK-493)
• A way to jump to a specific HK number if you don't even know what page it's on (example: http://www.so-calleddollars.com?HK-461

Of those, the site-wide search is clearly useful, the others maybe less so.

About a year ago, I made the side Mobile-friendly, so that it was actually usable on phones and tablets. That was definitely helpful to a lot of people.

Still, the site is mostly a web version of the printed book. More than a simple PDF, sure. Not much more.

In fact, there are very few web sites that in my mind could replace a printed reference for that subject. There are plenty of numismatic web sites that are useful. This site is useful. The Heritage archives are useful. And yet the information on those sites is a different sort than what you find in standard printed reference. I use those in addition to everything else; they don't replace anything.

What would you want to see in a web site that was designed to replace a subject-specific printed numismatic reference book?