get values of number boxes (and other objects)

Indeed there is. It's probably not documented because there's no JS
function for it per se, but you can build your own. Below is an
example of how to retrieve the names of all matrices in a patch. The
basic technique is to iterate through patcher objects and use the JS
functions connect()/disconnect() to invisibly talk to patcher objects
without a user ever seeing actual patch coords.

wes

-------------------clipping: gathermatrices.pat

---------------

---------------js: xray.gathernames.js-------
var p = this.patcher;
var obj;
var matrixNames = new Array();
var counter = 0;
var self = this.box;

function bang()
{
counter = 0;
obj = p.firstobject;

//limit search to first 100 objects
while(obj && counter < 100)
{
if(obj.maxclass == "jit.matrix")
{
p.connect(obj, 1, self, 0);
obj.message("getname");
p.disconnect(obj, 1, self, 0);
}

obj = obj.nextobject;
counter++;
}

fillmenu();
counter = 0;
}

function name(matrixname)
{
if(! alreadyexists(matrixname))
matrixNames[matrixNames.length] = matrixname;
}

function alreadyexists(matrixname)
{
var exists = 0;

for(i=0; i < matrixNames.length; i++)
{
if(matrixNames[i] == matrixname)
{
exists = 1;
}
}

return exists;
}

function fillmenu()
{
outlet(0, "clear");

//make ubumenu prepend
outlet(0, "prefix_mode", 1);
outlet(0, "prefix", "name");

for(i=0; i < matrixNames.length; i++)
{
outlet(0, "append", matrixNames[i]);
}
}