My opinions on crediting are as follows.
I think it's important to give credit: to scans, brushes, vectors, styles , or pretty much anything you use that you didn't create in a vacuum. Even if the source didn't ask for credit, do it anyway. For one, it's humble and shows appreciation for the resources you work with; secondly, it develops a little network of friendly references and helps others find resources that they can also use; thirdly...
Of my interest in anime and manga, I enjoy Naruto the most. I do a bit of graphic manip, building LJ communities, and buying useless Naruto stuff because I like the pretty pictures.
As for graphics, I don't generally work with areas as large as wallpapers. I tend to do small things, like icons and banners. Maybe one day I'll step up.
Find more of my stuff here: http://kylara.livejournal.com/profile
I scan and release shounen manga chapter here: http://www.mangahelpers.com
~~~ IF YOU USE MY SCANS: ~~~ - Please credit me (as Kylara, or as Geraldine @ animepaper, either works). - Please do not upload my scans to galleries that earn you credits for uploading, e.g. Minitokyo and AnimePaper. - Please do not host my scans behind a donation or plus account <wall.< - Do not in any way use my scans to make money.
Also: I'm not needy. If you don't like my scans, don't use them.
I give the best I have, that's all I can do.