max-len.js

// Minimal MaxLength validation on jQuery
// Expected markup :  <textarea class="maxlen 250"></textarea>

jQuery("textarea.maxlen").live("keyup", function(event) {

    var max = parseInt(this.className.match(/\d+/));
    var key = event.which;

    if (max && (key >= 33 || key == 13)) {
        if (this.value.length >= max) {
            this.value = this.value.substr(0, max);
            event.preventDefault();
        }
    }
});

numeric.js

// Numeric only input
jQuery("input.numerical").live("keyup", function(event) {
    var key = event.which;
    jQuery(this).val(this.value.replace(/\D/ig, ""));
});