I know theres that Ivy Generator knocking around and the results are fantastic, but I'd like to share a fairly simple technique I've used in the past in photoshop. In my latest image i used it to give detail to a fairly bland wall that was in the final render. All you need is to find a  decent resolution picture of some ivy or similair leaves.  1. Drag the ivy image onto the render and resize it according the the scale you wish to paint. 2. Select the clone tool and a suitable sized hared edged brush, I varied between 1-3 pixels for this. 3. Clone from the ivy to the area on your picture, until you are happy with the results Then erase the ivy image but not the bit you've just cloned obviously 4. Use the eyedropper tool to select part of the image that appears as a shadow. Then go to Select >Load selection and click ok. 5. Create a new layer beneath the ivy layer which will be for the shadow.Using the paint bucket tool fill the area that is selected with the shadow colour you just selected. 6.Finally you can then just move the shadow layer just slightly out of sync with the Ivy layer to correspond with the direction that shadows fall in other parts of the render.

Thanks!  I copied this and I'm going to try it.

Forgot to say, you can duplicate the ivy layer and mess around with the colours and saturaion so you get brown leaves mixed in with green ones just give it a bit more depth.

I really like the idea of this..and thanks for letting us newbies in on it.  :D
I work in Paint Shop Pro and I don't see any problem in implementing it there.

Also if you have the ivy on a seperate layer you can use layer effets to get a very nice dropshadow IIRC...not at work 2 day so I can't check in PS CS.. ...

Love this method. Nice quick tut also!

Thanks guys...this is all very helpful.