AsT just released v1.131 of his graphical tool named iMPdraw. It’s a WIP, so it is time to suggest all the features which may be useful to you in this dedicated thread. AsT & TotO are currently working on the v2.0, managing fullscreen pixelart work.
Download: iMPdraw v1.131 (Impact).zip
Website: http://pushnpop.net
CPCWiki Thread: http://www.cpcwiki.eu/forum/