Not sure if this was already mentioned, but it looks like you can now "hide" apps from your purchased section in the iTunes store. If you open up iTunes and go to purchases and hover your mouse over an application you should see a faint X on the upper left corner. This doesn't permanently get rid of it, but you will need to go into your account settings and unhide it if you want to see it again. Good way to get rid of all of those free trials you downloaded.