Every software have their parameter tweakers,but XNA is not,I have made a GUI terms with sliders and float numbers for users to tweak with for changeing something like HLSL parameters  value etc..

use age: for camera: 1.use right mouse button to rotate the camera.

                              2.use mousereel to zoom+/- the view.

for parameters : 1.load the Helper.cs and Camera.cs to any scene you work with and have fun with it;

2,use mouse left or right button to increase or decrease the value for the float number underside.                       

2.feel free to use sliders value with simple mouse click on it.

you no need to know how it work just use it and add slide numbers as you like.also the code is very clean and not any"@!#" in it.

http://cubecg.zoomshare.com/files/Camera_test.rar

the pichttp://cubecg.zoomshare.com/files/GUI_XNA.jpg