Be able to filter games to show the most sales per day first

when you say "several email reminders will be sent before deleting your collection" actually send several, not delete it after the first like you did to mine.

Would be great to get the full list of all portal characters so I can fully update my collection.

There are people that want cover art work for there games. It is hit or miss on cover art / box art online. Some of the time you have to go with a variant art work. I would like to see the ability to print a full cover art work page off from the listing of your games. 

would love to have this on the list too

Greatest hits versions look hugely different than the original printing (also called "black label") of the game.  They look different, they're less desirable to collectors, and therefore are usually cheaper than the black label version of the game.  

Not including the ability to differentiate greatest hits/player's choice from the black label editions of a game also distorts average price since the cheaper greatest hits sales lower the averages of the black label games. 

There is only the collector edition in the database

If it was possible to add guidebooks to collection that would be awesome.