wgt_genres.php

<?php
define('LASTFM_API_KEY', 'xxx');

function callApi($url, $data = false)
{
    $curl = curl_init();
    if ($data) {
        $url = sprintf('%s?%s', $url, http_build_query($data));
    }
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    return curl_exec($curl);
}

$response = json_decode(callApi('http://ws.audioscrobbler.com/2.0/', array(
    'method' => 'event.getinfo',
    'event' => '3600736',
    'api_key' => LASTFM_API_KEY,
    'format' => 'json'
)));
$artists = (array) $response->event->artists->artist;
natcasesort($artists);

foreach ($artists as $artist) {
    $firstLetter = strtolower(substr($artist, 0, 1));
    if (!isset($lastFirstLetter) || $lastFirstLetter !== $firstLetter) {
        echo strtoupper($firstLetter) . "\n";
        $lastFirstLetter = $firstLetter;
    }

    $response = json_decode(callApi('http://ws.audioscrobbler.com/2.0/', array(
        'method' => 'artist.getinfo',
        'artist' => $artist,
        'api_key' => LASTFM_API_KEY,
        'format' => 'json'
    )));
    $tags = is_object($response->artist->tags) ? (array) $response->artist->tags->tag : array();
    if (array_key_exists('name', $tags)) {
        $tags = array(ucwords($tags['name']));
    } else {
        array_walk($tags, create_function('&$v', '$v = ucwords($v->name);'));
    }

    echo utf8_decode($artist) . ' [color=#004080]' . implode('/', $tags) . '[/color]';
    echo "\n";
}