Here's a really great site for some pretty sophisticated free downloads.
Digital Media Designer - Adobe Photoshop design software, design software, Adobe Photoshop, Adobe Photoshop filters, photoshop filters, web design software, desktop publishing software, desktop publishing, Desktop Publishing Software, graphic design
It's actually a site written for MAC users, but most of the downloads are made for either MAC or Windows. scroll down the list and find the goodies that appeal to you. At the bottom, click on Downloads Archive and it will take you to the next page of downloads (it goes on and on and on...... many pages). You'll have to go through this way to find the custom shapes, but they are worth finding.
Look for the stuff by Dave Nagel...he does some fantastic work, and with every page of his downloads, he gives a really good explanation of how to install and use them.
I particularly like his brush sets.... there are 43 sets of them posted so far, and they will blow you away
Lately he is doing a Displacement map series.
Please excuse my enthusiasm, but I've been a fan of Nagel's stuff for some time now....take a look.....I bet you'll find something you like.
And, while you're there, click on tutorials (in the list, upper left)....the site has a ton of great tutorials too.
photofixer