Of course you know already that in Jdeveloper you can create xsl maps, just by drawing lines between source and target elements. In many cases you need functions or complex expressions in between. Those are "drag-and-dropable" as well. I found that you can even drop a function on a line and the function will be added to the expression. So with a little thought of the sequence of "drag-and-drops" of functions you can assemble pretty complex expressions together just by using the mouse. Although I'm not affraid to hack back in the source code of the xsl for quickness, I found that this allowed me to spare a few switches between the Design and the Source tab. That is convenient, since hacking the source and switching back to the Design tab will cause the Designer to initialize again, driving you to expand again all the nodes you were working on. Understandable, but inconvenient with large XSD's.

What I did not know until recently is how to set a variable to an element. So what I did before was to hack in the source a piece of code like:

<ns0:countryCode>
  <xsl:value-of select="$landCodeNL" />
</ns0:countryCode>

It turns out that you can do that by "drag-and-drop" as well. In the component-palette you need to select the "Advanced" functions:
 At the bottom you find  a xpath-expression element. Drag-and-drop that in the design area and connect it to the target element.





When you edit it you can just type in your expression, for instance just a variable. When you start with a dollar sign, it even gives you a drop-down-list with available variables. Just pick the right one and our done.

I admit, no high-standard tip, but convenient enough though, for me at least.