What programs do you use to make textures/objects/maps for Roll20 games?

I work mainly in GIMP, PS CS3 every now and then due to certain/ a lot of features.

I'm looking at DundJinni as it looks interesting and the quality of work that has come out of it is amazing.

I don't think you'll find features in Dundjinni not available in CS3 or Gimp.
The quality of the results is mostly due to the quality of the ressources available in Dundjinni (but the program could be worth it just for that).

One of the nice things about the different mapping software is that they nearly all use .png files. You can snag a lot of these objects and textures and use them in photoshop/gimp even. The dundjinni forums are filled with useful stuff, and a lot of it (and more) is archived on RPGMapShare.
I actually do use Dundjinni, but will sometimes finish my maps in PS for some extra effects.

I love the Dundjinni forums - they're a fantastic resource. I did not like the program itself; it's a purchase I regret (specifically, the interface felt very clumsy and limited - it was hard to be precise with it).

If you want a huge collection of pose-able monsters and characters for tokens or portraits, first you need to download the free demo of World of Warcraft and then install the WoW Model Viewer from: http://www.wowmodelviewer.org/ You can play any of the included animations at any speed, pause them when you find something you like and then rotate the model around and around to find the perfect angle for your portrait or go straight up top for a top down token.

There's also tree.d, a lightweight program you can use to create a MASSIVE number and variety of top down tokens of trees. http://www.frecle.net/index.php?show=treed.about

I start with either Paper , Sketchbook Pro, MyPaint, Artrage depending on how I feel. Then I am off to Photoshop for the bulk. A lot of the content I did for Dundjinni was done in Paint Shop Pro. So there are loads of inexpensive options out there.

Using copy and pasting, I've found it pretty easy to take a few simple models and spread them around to make a rather complex and detailed map using Sketchup.

Here's something I just finished: