In Wolfram Mathematica, I can interactively modify the value of a parameter by using the Manipulate[]
command.
For example, Manipulate[n, {n, 1, 2
Update
This was added in IPython 2.0 (released Apr 1, 2014), it's called Interactive Widgets and works in web notebooks.
Original answer
This is ongoing work for 2.0 (release December something-ish) Have a look at the IPython-dev meeting on YouTube to see progress. The last meeting from oct 21 at 28min-ish has a widget demo by John then interact
by Brian.