PB: Spin Wheel, Discount Popup

I reviewed and tested several apps for this purpose & popupBoost was the only one that offered all the settings we needed. (We wanted to embed it in the page.) It's a ton of settings, but they are also really useful to get exactly what you need/want (including custom CSS, if needed). The coupon integration is really good - it will generate individual coupons where you can define the prefix, and you can customize the visuals a lot.

And the support - unbelievable! Unfortunately a new version had just been released before our promotion, but Nula fixed everything that came up immediately or helped me find the setting I was looking for.

Also, did I mention the value for the money? Anyway, so far, quite happy in general.