Well there are a number of options. Paint Shop Pro has a Color Sketch script that applies filters that are traditionally used in other editors to get the comic book effect.
The basic idea is to first duplicate the image onto another layer. Greyscale the layer and then duplicate that one as well. Set a negative image filter to this second greyscale layer. Then set the blend mode of this now negative layer to Dodge, it should go white. Then apply a blur filter to the negative image layer, Average is most common but other blur modes also work. One that allows you to set the level of blurring is best. This is like a pencil sketch effect.
Finally you take the original image and put it above all of the other layers and set the blend mode to burn. In Photoshop it's linear Blur.
Now I don't know about plugin filters that do any good jobs but I do have a few options other than just this small method.
One example that I wish we had more of a point to point match on is this Photoshop tutorial http://www.photoshoproadmap.com/Photosh ... ok-effect/
Paint Shop Pro does not have a Film Grain effect or a layer stroke effect. It does however have the halftone filter so something can be done to work around what Paint Shop Pro lacks.http://www.comeeko.com/
Is a webservice that allows you to create comics out of photos, but I'm not overly sure if the average user would want to use it....hard to say. Here's a tutorial written on using this service. http://www.ampercent.com/turn-pictures- ... line/5462/
IntoCartoon is a piece of software that does comic like effects for your photos. It's not really expensive but not everyone would be willing to spend the money. There is a trial version of the pro version of the software if you'd like to check it out though. http://www.intocartoon.com/
Befunky is another webservice that offers the cartoonizer effect. http://www.befunky.com/features
And that's all I've got. I'm sure there are plugins for this sort of thing that work with Paint Shop Pro, PhotoImpact, and Photoshop but I never took the time to find them.