I second having Sky Render's excel sheet implemented into the website.
I'd also like to see being able to have select 4 or 5 consoles/games to compare each other to. This would make it easier to compare all the current gen systems.
Also a possible change to (or whole new area) the hardware table / graphs by date. Make it so we can select the beginning date, and then the number of weeks, for each system independently. That way I could select PS1 starting first week in Jan, and compare it directly to PS2, starting first week in Jan, and going for 52 weeks. The way it is now, I have to look up PS1, select first week of Jan as start, and then last week in Dec as end for the year 1998, and then do the same for the PS2 except for the year 2003 (for example). Being able to have it in one table or graph (especially graphs, making it easier to compare) would be great.
I would do this myself and put it into Excel sheets (since I would really like this feature to help with my comparisons, and which would add other nice features like, being able to see the week with highest sales in a given time period), but I'm afraid I don't have the time to do something like that. If there was a way I could like "download" the data off the website without having to do it manually (i.e. look it up and then copy-paste into excel) I could probably do it.