The first 3 are my favourites :).
God ones man, keep it up!
Detailed criticism time o_O:
The mountain – very nice, the texture of the mountain itself is kinda strange, and the yellow lines (sun rays?) are kinda unrealistic, but pretty cool overall :D.
meteors – awesome picture, the style is excellent and the shading of the fire is also very nice :D.
forest – my favourite, looks very detailed and eerie :D.
Jimmy – not bad, but looks like pixelated and strange ;P.
Tree on Fire – I had no idea what iwas until I saw the name xP, you could try to make it clearer and less blurry.
Sketch of Tree – not bad, but you might want to work on getting the branches to look more crooked, and you should work on the overall texture of the tree :P.
Overall, I like your style, keep it up :D!