Kyle Hayes pinged me with an interesting question today. He wanted to run a custom tag in "end" mode - but inside a CFIF block:

This of course won't work - it will throw an error. Luckily there is a way around it, and I discuss it here in this blog entry from 2004:

Manually Setting Execution Mode

p.s. This entry is basically a pointer to a way old blog post of mine. I figured since the question came up it was ok to repeat it. Good idea? Bad idea? Waste of space?