I use Poser 7 for my 3D images. Other tools that are part of my work flow are:

GIMP - why? because it is free ware and is very easy to use; and does not take up a lot of system resources. It is very easy to toggle back and forth from an open Poser window to a GIMP window and test a texture or a mat file. Also, GIMP handles many different file types.

Photoshop CS2 - why? well, since it is an industry basic, there are occasionally some things that are simply just easier to do with a more powerful image editor; however, I find I use Photoshop very rarely these days.

Wings3D - why? well, again, a free ware application, and a very simple to use 3D modeler. Still learning some of the more advanced things that can be done with Wings, but overall, a very simple and remarkably powerful little program. I use if for simple objects, and not for large 3D scenes.

Curvy3D - a fun, simple little 3D application. Has a quirky interface, builds 3D models based on 'curves' that the user draws. But, does have the ability to make some useful objects.

Adobe Illustrator - I really like Illustrator, though use if rarely these days. I like the vector files it outputs, which are more versatile than jpg's for example when doing a lot of image scaling. Though part of the tool kit, I am using this very rarely these days.

IrfanView - a nice free ware image viewer; also has the ability to scale and do some basic format conversions.

At any rate, these are the basic apps that I use these days.