duck

-- SequenceItem.js --

private static var numItems = 20;
private static var items : Transform[];

public var index = -1;  // (value when not set)

function Start() {
    if (items == null)
    {
        // probably needs error checking: will fail if objects not named/don't exist/don't have script attached!
        items = Transform[numItems];
        for (var n = 1; n <= numItems; ++n) {
            items[n] = GameObject.Find("item "+n).transform;
            var sequenceItem : SequenceItem = items[n].GetComponent("SequenceItem");
            sequenceItem.index = n;
        }
    }
}

function OnMouseDown() {
    // need error checking here
    var nextItem = items[index+1];
    var prevItem = items[index-1];
}