Hello Gooney,
nice to see people making their work available.
Looking at your work I might have some pointers on areas that could be increased in future work.
Your skins tend to look a tad "flat" or artifical as the colors are really even and bright and the panellines more likely look like painted over the plane surfaces rather than being part of the plane. You should reduce their opacity and add some depth to them by dublicating them and brightening the created set and move it off by one pixel.
If you read through this page's tuts you should find lots of materials to find out how to get the color finish looking more like the real thing. Maybe adding some "texture" to the color. Otherwise they look a bit odd and out of place ingame imho.
Just some my personal opinion mate. I think you basically got it and with some tweaking they can be really nice work!
~S~