if you want a gui equation editor, check out lyx [http://www.lyx.org/], which uses tex as its backend. texmacs [http://www.texmacs.org/] is another option worth exploring.
Texmacs often get recommended, but I haven't seen any arguments for it that are compelling. I guess there must be a case for it, else no one would work on it. What do you like about it?
TeXmacs is a true WYSIWYG scientific word processor. It's not a TeX/LaTeX GUI front-end. Rather, it has its own typesetter that produces quality comparable to TeX in real-time as you type.
it's a decent middle ground between the clunkiness of wysiwyg word processors and the typing-to-reward ratio of pure markup. personally i prefer just writing markup in ascii, but if you want some of the control of tex, but dislike doing that much typing, texmacs or lyx might be just what you are looking for.
kile is more of a lyx competitor (latex frontend versus latex ide). texmacs has its own rendering engine; despite the name it does not in any way depend upon tex.
I can recommend LyX as well, it makes authoring LaTeX documents much easier. The formula editor is nice, and it makes editing tables a lot more convenient.
