PocketInformant blew away anything Palm had... Though I always preferred Palm. I bought both Agendus and Datebk5, and used them heavily. But PocketInformant made WinMo more than bearable...!

I also used ShadowPlan a lot, and loved its integration with the system-wide calendar and todo databases (one key thing we don't have on Maemo).

I've put some cash into great PIM apps... and still very willing to do it again.