Coded one in JavaScript (using no images), although I wouldn't suggest using this as I haven't tested it properly and it makes the browser really slow.
Example: http://joshjh.pwp.blueyonder.co.uk/wave/
var waveStructure = new Array(), amplitudeDirection = 'u', rand, adj, nextWave;
function structureWave() {
rand = Number(Math.floor(Math.random()*100))+1;
if(rand<21 && amplitudeDirection == 'u') amplitudeDirection = 'd';
if(rand<21 && amplitudeDirection == 'd') amplitudeDirection = 'u';
adj = Number(Math.floor(Math.random()*15))+1
if(waveStructure[0]==undefined) waveStructure[0] = 10;
var previousWave = waveStructure[0];
for(a=0; a<adj; a++) {
if(amplitudeDirection == 'u' && waveStructure[0] == 30) amplitudeDirection = 'd';
if(amplitudeDirection == 'd' && waveStructure[0] == 0) amplitudeDirection = 'u';
if(amplitudeDirection == 'd') nextWave = Number(previousWave)-1;
if(amplitudeDirection == 'u') nextWave = Number(previousWave)+1;
waveStructure.splice(0,0,nextWave)
if(waveStructure[150]!=undefined) {
waveStructure.splice(200,1);
}
}
}
function printWave() {
var HTML = '';
for(b=0; b<waveStructure.length; b++) {
//HTML += '<img src="pixel.gif" style="margin-bottom: '+waveStructure[b]+'" />';
HTML += '<div style="width: 1px; float: left; height: 0; padding-top: '+waveStructure[b]+'"><hr width="1" align="left" noshade="true" color="#000000" /></div>';
}
document.getElementById('waveBox').innerHTML = HTML;
structureWave();
}