SNOM 821 versus SNOM 870 v2
The mini-browser in itself can be quite useful.
The following wiki provides all of the info which is useful to help develop such applications: http://wiki.snom.com/Category:HowTo:Minibrowser
There is an example on there for using a web cam.
You can use a combination of action URLs and Minibrowser XMLs to create call reporting type features - such as adding the last caller to a database. In itself the minibrowser does not offer many uses, it simply offers the possibility to create small web apps.
The touch screen isn't just a gimmick but rather something which is still in its infancy and therefore may just require further software development.
You can make call transfers and setup conference calls just by dragging calls around on the screen. This makes the SNOM 870 more slick when doing these things and the larger screen resolution does enhance the experience.
The SNOM 870 and SNOM 821 have the same features - the only real difference is the touch screen and that may attract users who are after something a little more cutting edge which they are willing the pay a premium for.