The Drupal date_timezone module (part of Date) lets you use city names instead of timezone offsets in order to select a timezone, and that picks up Daylight Savings Time rules in a reasonably good manner, too.

A long list of cities can be hard to work with, though. This list is equally long, but it’s organized by GMT offset, which people are also likely to know.

Index: date_api.module
===================================================================
--- date_api.module	(revision 2404)
+++ date_api.module	(working copy)
@@ -490,6 +490,14 @@
           }
         }
       }
+
+      // Now reformat the zonenames so that they're of the form (GMT+0800) Asia/Manila
+      foreach ($zonenames as $name => $zone) {
+        $x = date_make_date('now', $name);
+        $list[$name] = '(GMT' . date_format($x, 'P') . ') ' . str_replace(' ', '_', $zone);
+      }
+      asort($list);
+      $zonenames = $list;
       if (!empty($zonenames)) {
         cache_set('date_timezone_identifiers_list', 'cache', serialize($zonenames));
       }

There’s probably a much more efficient way to do this, but hey, it works.