You should add a price between feature in the collection part.  Sometimes I like to see how many games I have that are $20 and up, or between $20-$50 and would be cool to just click a couple things instead of having to scroll and count.  

I usually use a mobile Web version of the site so if this is already a feature through a different source please disregard.

Every so often I'd like to make a donation, but I don't see any options available. If PriceCharting just put a bitcoin wallet address in the webpage footer, I could send a few dollars whenever I wanted.  It's simple and I wouldn't need to log into a PayPal account or purchase anything. 

my collection view, add check box for each item on the main view and allow me to sell the batch

Completed listings are usually within about a $2-5 margin of error from my experience between this site and EBAY. Often it will be larger if the listing exemplified is a month or two out of date (which seldom occurs, but does, and can throw off the perceived valuation.

Linking to TRENDING values would help to minimize that margin of error :)
 

The ability to select a preferred currency or even an exchange conversion (you can link to google exchng if you email google they may advise on how to setup the app).

Include value for the gray variants for games like Bassmasters 2000, Road Rash, and others as they are significatly different from their colored variants often times.

You need a option to see everything available on one list.

Why is there no values for Nes 5 screw variants. Everyone knows the 5 screw variants fetch higher prices than there 3 screw counterparts. Particularly the rares: megaman 1, Mike Tysons punch out, star force, alpha mission, jaws and gotcha. I am a variant collector and have yet to see a variant price guide anywhere and would love to have such a thing for my hobbie