Auto scale the yAxis with Flot and the selectable plugin

gistfile1.js

                $("#placeholder").bind("plotselected", function (event, ranges) {
                        var ymin, ymax;
                        var plotdata = plot.getData();

                        $.each(plotdata, function (e, val) {
                                $.each(val.data, function (e1, val1) {
                                        if ((val1[0] >= ranges.xaxis.from) && (val1[0] <= ranges.xaxis.to)) {
                                                if (ymax == null || val1[1] > ymax) ymax = val1[1];
                                                if (ymin == null || val1[1] < ymin) ymin = val1[1];
                                        }
                                })
                        });

                        $.plot("#placeholder", plotdata, $.extend(true, {}, options, {
                                xaxis: {
                                        min: ranges.xaxis.from,
                                        max: ranges.xaxis.to
                                },
                                yaxis: {
                                        min: ymin - 10,
                                        max: ymax + 10
                                }
                        }));

                        overview.setSelection(ranges, true);
                });

A few minor sugestion:
I would sugest rescaling the y axis as a percentage, instead of a constant. And setting the ymin to 0 if it's positive.

            ymin = ( ymin > 0 ) ? 0 : ymin;
            extraY = ( ymax - ymin ) * 0.07;
            ymin = ( ymin == 0 ) ? 0 : ymin - extraY;
            ymax = ymax + extraY;

            $.plot(graph_holder, plotdata, $.extend(true, {}, options, {
                    xaxis: {
                            min: ranges.xaxis.from,
                            max: ranges.xaxis.to
                    },
                    yaxis: {
                            min: ymin,
                            max: ymax
                    }
            }));