XPS MultiQuant (Freeware)
Practical tool for not only peak fitting but also quantitative analysis
Fityk (Freeware)
Easy but powerful software to do general peak fitting including Voigt shapes and removal of Shirley background.
Export of points of all fitting curves or peak parameters.
Source code available!
Quases
An expensive software from XPS pope S. Tougaard, some nice examples on the website showing how sophisticated XPS fitting can be!