My First Flex ArcGIS Server App was to create a reusable Toolbar with (zoomin , zoomout , pan , zoom to full extent , zoom next , zoom previous) that i can use in all my Flex applications with the ability to set the orientation of the Toolbar (vertical or horizontal), anytime u need toolbar u just have to drag and drop from custom and set two proprties and ur done.
you can view a sample HERE and as its goning to be always you can get the source code HERE
just set 2 properties, ApplicationMap to you Map Id and the ToolbarDirection to horizontal or vertical and ur done