Im not sure but, I believe many photoshop brushes can be used in Jasc Paint Shop Pro as well.
Thanks to $umboody for this list:

(1) 8Nero - A selection of around 200 real quality brushes

(2) PhotoshopBrushes.com -
Really nice, good quality brushes. Good selection as well

(3) MissM's Brushes - A small collection of good brushes

(4) Photoshop Support Brushes - Tons of good stuff, a bit hard to navigate

(5) Deviantart Brush Directory - Huge collection of community-made Photoshop brushes. There are also tutorials and other resources for PS and other image manipulation programs. Make sure you search by number of favourites to get the best stuff first. Well worth more than a look

(6) FreePhotoshop.com - Large collection of small brushes, to be used with painting and whatnot

(7) About Photoshop Resource - Small set of useful brushes

(8) Echoica Brushes - Quality brushes (make sure you link back to echoica.net if you use these brushes)

(9) Dubtastic Brushes - Nice collection of good brushes

(10) Google.uk Photoshop Brush Search - Your friendly neighborhood search engine results.

(1) Hybrid Genesis - Icon and General brushes are available.

(2) V Brush - Nice collection of brushes and fairly large as well. Brush tutorials is available too.

Angelic Trust-A great place where you can find some cute brushes.
Darkwaif's Phantasy Gallery-Another place where I found some really cool brushes.

(1) Blinding Light Brushes - Linkware Photoshop brushes
(2) Beautiful Sin Brushes - Really sweet brushes.
(3) Biorust Brushes - Very useful, well organized list of brushes
(4) Blue Feelings BRushes - Kind of annoying to navigate but some useful brushes can be found here.
(5) Finfond Brushes - Photoshop 6 Brushes. Old but some are unique.

MAGITEK DESIGNS there are many brushes, galleries, wallpapers and forum n_n

www.celestial-star.net

lots of brushes, tutorials and much more!