Sublime text 2 or coda 2.0 would work great.
Photoshop is awesome. I love illustrator too.
Gimp is a free alternative to photoshop and cool.
http://www.gimp.org
For "learning purposes" check out "CSS Hat" a plug in for photoshop. Haven't used it but looks useful for those learning or to speed up your workflow(not as a crutch)
https://www.google.com/webdesigner/ is a free tool I just saw. Haven't used it yet.