[dBHEAD]

Vari-Fi will do this. I have used it for exactly that effect. It can imitate tape slowing down to a stop or speeding up from a stop. Very easy to use. You simply highlight the segment of a region yo want to process, designate whether you want it to speed up or slow down, and click PROCESS. To the best of my knowledge, there is no limit to the length, so you can have it slow down over the course of a full minute, or go from full speed to a dead stop in seconds.

I should point out, though, you can't really automate it. You can, however, chop the audio up into multiple regions and apply it to each one.