Shading, eh? Allright, let's get cracking on this. I'm going to show you how to create my new splash image.
I was going to make a tutorial on making my interface, but I would have had to reconstruct the entire thing, and that would have been boring. The splash screen, on the other hand, was yet to be done, so I figured I'd kill two flies with one swat. (If that sounds strange, it's because it's a Finnish saying, and while I'm sure it's used elsewhere in the world, too, I don't know what the exact english equivalent is...)
So, you'll learn to make my splash screen here. Hopefully. Whatever it turns out to be. Note that this tutorial may contain some unnecessary steps, since I'm writing this as I make the image, and I haven't planned much.

The way we start, is, unsurprisingly, by making a new image. 450x200 seems like a nice size.
The background should be black, since the rest of the site is, too.

Let's plot out some shapes. Create a new layer, and draw a shape like the one in the top left corner with the polygonal lasso tool, and fill it with gray. Create another layer, placing it under the layer with the corner bit, make a rectangular selection and fill with green so you get, surprise, surprise, a green rectangle like the one below. Create a 3rd layer, above the green bit-layer, and below the corner bit-layer (Hey, I like layers!) and draw out the darker gray bits you can see below with the polygonal lasso tool, and fill with gray. I used a darker shade, because that way you could see the edge of the corner-bit. (Damn, I've gotta think of something else to call these things...)

Let's shade a bit, so we can see where we're going with this. Whip out the burn tool, set it to midtones, and select a nice, big brush, say 100 in size. using a multitude of layers comes in handy now. Just select the layer you want to shade, and shade away! First I made the shadows, then added a highlight or two using the dodge-tool. Remember, that you can just press ALT (I think that's the 'option' -key for you Mac people.) to use the counterpart of the tool you're using. So, if you've got burn selected, and want to use dodge a bit, press and hold down ALT, and dodge away! Use as large a brush as possible, since you'll get smooth transitions from one shade to the next this way. If the brush you're using seems too clumsy for what you need to do, move down to a smaller brush. Keep in mind the direction of the light. In this case, it's supposed to be coming from the top right, so make the highlights and shadows accordingly. Try to make something like what you see below:

Now, the interface has a part like the corner here, and it has a sphere in it, so let's make one here, too.

Create a new layer, make it the topmost one. Use the elliptical marquee tool to create a spherical selection. Press down the SHIFT - key to get a perfect sphere. Select the radial gradient tool, and set your foreground color to white, and the background color to black. (The fastest way to do this is to press D and then X) make a gradient, starting where the highlight of the sphere should be, and ending at the edge of the selection. I pressed the SHIFT key while doing this, so the light comes in at a nice 45 degree angle.
The sphere, I think, shouldn't just float there on top of everything, so expand the spherical selection you should still have active by 2 pixels.
select the layer with the corner-bit and press DEL to clear the selected area. Now the sphere has someplace in specific to float in.

As you may have noticed, the highlight of the sphere has been enhanced a bit from what it was after applying the gradient. I used image > adjust > levels with these settings to achieve the effect:

Well, now. The hole in the corner-bit reveals some stuff beneath, and it looks too bright right now. Select the ... Um, OK, time out. The corner-bit-layer is, as of now called Mr. Corny, the layer with the slightly darker gray bits is Ms. Sleek, the layer with the green bit is Mr. Green, and the layer with the sphere is Mrs. Sphere. Good? So, select Ms. Sleek, and darken the area that should be overshadowed by Mr. Corny a bit using the burn tool. (Hm, naming layers in such an affectionate fashion can be fun. I'll have to try and make a children's story this way some day...)
Well, while we're shading, let's have a look at some other stuff.
Ms. Sleek could use some highlights, especially at the topmost edge. Spiff that area up a bit with the dodge tool, set to midtones. Use a brush size of, say 35. The bit of Ms. Sleek we can see coming out from underneath Mr. Corny ath the bottom of the image(Oh shut up! This is a tutorial, for crying out loud! There's nothing kinky about this!) needs something too. Add a highlight to the right edge there, using a slightly smaller brush than size 35.
Now for Mr. Corny. He needs to have a stronger shadow in the bottom left corner, so give him one, using the burn tool and a large brush. Then add some highlighting at his top part, as seen below. Oh, and maybe have Mrs. Sphere cast a shadow over him.
Let's move on to Mrs. sphere. She's not exactly young anymore, and isn't afraid to show it. Bring out her brave side ans add some scratches! Use the burn/dodge tools with the smallest brush size to add a few scratches like below. don't go overboard, though. Mrs. Sphere isn't a scarred warrior...
Now, Mr. Green wants to be a screen. Let's fulfill his wishes. Select a brush size of 65, and add sme long highlights and shadows to his surface, like below. Maybe darken the shadows cast by Ms. Sleek and Mr. Corny a bit. Then, for that nice touch that'll make Mr. Green extra happy, add some highlights to the right and bottom edges. First just lighten the edges up a bit with the dodge tool, using a brush size of 35. Then move down to a slightly smaller brush, and lighten the edges up again a bit. Move down to a smaller brush and... You get the point. Continue until it looks good.

Now, Mrs. Sphere doesn't look very shiny, does she? Let's add a reflection. I've taken quite a few photos of old buildings and such stuff in the city I live, so I have a nice archive of images to pick from, when I need them. I decided to use a photo of a railroad track on a bridge, taken from underneath the bridge. You can use a photo of your own, or download the pic I used here.
Place the photo on a new layer above Mrs. Sphere and set the layer to Soft light. Select the transparency of Mrs. Sphere, and use filters > distort > spherize at full strenght on the photo layer. If Mrs. Sphere looks like she could use some shine, add some with the dodge tool.

Mr. corny and Ms. Sleek are metal and need to look sharp. This can be achieved by highlighting their edges. Use a smallish brush. You'll probablly need to set the dodge tool to highlights. The results can be seen below.

I'd say it's pretty much ready, except of course it needs text. This is, after all, a splash image. Oh yeah, and if there's unused space in the image, just crop that out.

I may well change the font I use right now, I just didn't have anything better at the moment. I'll have to pay fontfreak.com a visit.
Here's the result, anyhow: