Using resources from Deviant Art is a very bad idea in my opinion!
Most of them are not really free, some have only licenses mentioned on external websites and so on! If you use their stuff you will never be able to create something that can be released under the typical Glest license cc-by-sa v3.
My strong advice: DON'T USE IT! ( beside the tutorials of course )
Use really free sites like the one I always suggest: http://www.burningwell.org
I have never had a problem with using DeviantArt as a resource, I still maintain that it's a great place for resources. If you are worried about licenses and whatnot, then don't be afraid to contact the artists.
Most of the people on there are more then happy to let you use their work, and most licenses mentioned are used as a safety precaution to make sure the artists get credit, which I always make sure to give, as well as make sure that people aren't making money off of their work. Last time I checked, Glest was an open source game, and didn't make any money.
Just make sure you use discretion, which is something everyone should do when looking to use free resources anyways, regardless of the site.
I'll definitely check out your site though, thanks.
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Also, for those looking for fonts, I have found
http://www.dafont.com/ to be a great resource as well, it also tells you whether or not the font your downloading is able to be used for commercial use.