Hey,
First - thanks! Use this thing everytime I'm in EC. A few suggestions:
1) Although the plots are beautiful, have you considered something a bit... nicer? (e.g.
http://pchart.sourceforge.net/screenshots.php?ID=2)
2) Things are a bit messy with duplicates, fake things, badly parsed things, etc. Either (a) a master list of items with aliases that get mapped to the item, or (b) a way to link two separate names so that they are known to be the same thing (i.e. "aon" and "amulet of necropotence").
3) Market trends above just item by item. For example, the top 20 most traded things and their price trends with time. Volume/number of trades with time. Some measure of inflation / plat in the economy with time.
4) Few parses things which are handled badly now:
"bracers x2" -> "bracers x" (with some weird price I suspect)
"reed belt - zaharn's coronet - diamond - brigine tunic" (dash as an item separator)
abreviation grouping (i.e. "plat"->"platinum", "rubi"->"rubicite")
"selling" as a WTS tag
thats all for now