I am always having some kind of promotion such as 10% of storewide, economic stimulus sales, etc.

I am currently giving away a free product when a customer purchases $500 or more. I am wondering if I can have that free product automatically added to the shopping cart once the total reaches $500.

I was thinking of something like this too. I have an item I want to give away at a certain dollar amount.
I was thinking though, of a button they can click once they are eligible. However, it also needs to have a facility to remove the item if they change cart contents and drop below the required amount.

I already have some things in place that cover part of this, and I may take a stab at it.
I'll post back if I can work it out.
Let me know if you find a developer that wants to tackle it too.

David