Loop Forms[-][--][++]

Example, loops all checkboxes on page with certain name and alerts if they are checked
Note: masterform is the name of my <form name='masterform' ...> variable

for (var i = 0; i < document.masterform.elements.length; i++) {
    if (document.masterform.elements[i].type == 'checkbox') {
        if (document.masterform.elements[i].name.substring(0, 12) == 'chk_project_') {
            if (document.masterform.elements[i].checked) {
                alert('You Checked: ' + document.masterform.elements[i].name + ' Whos value is ' + document.masterform.elements[i].value);        
            }
            
        }
        
    }
}

Loop Elements[-][--][++]

A bit different than looping forms, this will loop all elements (like divs, spans, links...).

Collapse or Expand certain divs and alter link text 
function toggle_wiki_headers(collapse) {
    //Toggle Header Content Div Display
    var divs = document.getElementsByTagName("div");
    for (i=0; i < divs.length; i++) {
        id = divs[i].id;
        if (id.substring(id.length-9, id.length) == '__content') {
            if (collapse) {
                document.getElementById(id).style.display = 'none';
            } else {
                document.getElementById(id).style.display = 'block';
            }
        }
    }
    
    //Toggle Header [+]/[-] link display
    var hrefs = document.getElementsByTagName("a");
    for (i=0; i < hrefs.length; i++) {
        id = hrefs[i].id;
        if (id.substring(id.length-6, id.length) == '__link') {
            if (collapse) {
                document.getElementById(id).innerHTML = '[+]';
            } else {
                document.getElementById(id).innerHTML = '[-]';
            }
            
        }
    }

}

Capture Mouse Position[-][--][++]