Some good work, man. "Valesja and Landscape" is very nice. I'm no expert on pixel art, but I do love it (I plan to dabble in it sooner or later). If you haven't already, check out a website called pixeljoint.com. It's devoted to pixel art, and there's some really good tips in their forums.
http://pixeljoint.com/forum/forum_posts.asp?TID=12795
There's a really nice color palette in this link that I've fallen in love with. The user who made it is called Dawnbringer. I'm using it at the moment as a base color reference for a short two page comic I'm making.
Keep at it :-)