Cokin Filter System on my Canon EOS 400D

My newest purchase for my Canon EOS 400D camera is a part of the Cokin Filter System. It basically consists of a filter holder and an adapter for 58mm lenses. The filter holder can hold a variety of filters. The set I got from eBay consisted of 7 filters including stars, blue color, pastel and others.
Later, I bought a much desired gradient filter and closeup lens (+3). Compared to the price of individual screw in filters, Cokin filters only cost a fraction if you buy them on the used market as most of them only consist of a glass plate with some printing on it.
I'd like to give you a review of the filters I have got. It may help you decide if you want to buy the same for your digital or analog camera. I will continue this list as I gain more experience and probably more filters.

Diffractor Galaxy (42)
This is a very odd filter that adds rainbow like beams to point light sources. The effect is rather strong and I think it destroys more of the image than adds to it.

Star 4 (57 A)
This filter adds nice star effects to your image. You can rotate it and use it for point light sources like street lamps at night.

Parallel (58)
This works similar like the star filter but only creates stars with two beams of light. You can also use it for point light sources like this image.

Spot-Orange (66)
This is an orange glass with a transparent circle in the middle. I have not found suitable scenes where to use it yet.

Coef. + 2 BLUE (80 A)
This is a blue filter that makes the colors the image. I made some wonderful images with a cloudy sky.

Pastel 2 (87)
This filter makes the picture look much smoother, almost like a painting. I found it best for closeups and the effect destroys the image on wide angle scenes. But for flower pictures it really adds a lot to the image.

Close-up +3 (103 A)
This is a classic closeup filter that allows you to move your camera closer to objects.

Gradual G1 Grey (120 A)
This filter is a gradual gray filter. You can use it to make the sky darker than the foreground which helps you a lot when it comes to correct exposure in high contrast outdoor scenes. You could do this effect on your computer when shooting in RAW but for JPEG images you get best quality when using this filter. The filter is color neutral and you can rotate the filter holder to adjust the effect.