Creating Sprites in/for Unity

What are the most time effective options available to be able to create sprites within, or outside Unity ie. photoshop, and, in the case of latter, they obviously need to be portable for Unity. Any suggestions please?

There is a “Sprite Manager” by “Above and Beyond Software”. You could find some infos on their homepage or in the unity forum.

There is also a sprite manager in the unitywiki, don’t know if it is a previous version or something, just look into it: