I suppose you are using the Samsung Task Manager that was provided during the upgrade to 2.2 Froyo to check your RAM Manager (usage). My setup is 3 homescreens, with the following widgets:
Fancy Widget (clock & weather)
Business Calendar widget (4 x 3)
Springpad Large widget
Stock Power Control widget
Battery Life widget (Curvefish)
Ringer Toggle Widget
I have a mixture of folders (containing app and bookmark shortcuts) and some app shortcut icons directly on the homescreen.
My RAM usage is around 125-141/161 MB. Basically, one way to reduce RAM usage is to minimize the amount of widgets installed on the homescreen (e.g. launch the Facebook/Friendcaster app or the Facebook mobile website through a bookmark instead of using the Facebook/Friendcaster widget, SMS messenger app instead of widget, etc.) as those app widgets are actually running. Also, make sure you don't have unnecessary apps running or in a static state in the background by exiting an app properly using the <Back> key (you may have to click it several times) instead of the <Home> key which places the app in the background or may keep it running (e.g. TuneIn Radio) which you would only do if you intended to return back to that app after momentarily doing something else or if you were on a run and wanted to keep an app like Runkeeper running while you listened to TuneIn radio. Just remember to exit the running apps properly with the <Back> key afterwards.
Click on Menu->Settings->Applications->Running Services to see what's running and stop the unnecesary service there or click on Menu->Settings->Applications->Managed Services, select the app and Force stop the app if you need to stop a misbehaving app. Otherwise, the Android 2.2 OS is designed to manage RAM automatically, stopping low priority services to devote more memory to an app you are actively running and making Task Killers like ATK unnecessary