Alternatives to Qt

Here are a few C/C++ based cross-platform GUI frameworks:

• Qt
• wxWidgets
• GTK+
• FLTK
• FOX
• Ultimate++
• JUCE

The GUI Toolkit, Framework Page contains information about GUI frameworks for many languages and platforms.

Some other choices not mentioned so far:

XULRunner(Firefox's abstraction layer)

TK(bundled with python, bindings for many languages including c++)

Webapp (library for c++ web devel(inspired by qt) Wt)

Swing, AWT, SWT (if you are using java or other jvm languages)

One other option recommended by some is writing separate guis?(I don't necessarily agree but it should be mentioned).

wxWidgets is an another crossplatform option: https://stackoverflow.com/questions/2886258/wxwidgets-vs-qt

But why can't you use Qt, is there something missing in Qt that you would need? Or do you want another options just for the sake of options? It isn't Qt's fault that there aren't more crossplatform frameworks.