Originating in France, these durable outdoor lights are really nice for yards and gardens and don't need to be taken in...ever. We left ours up last winter and they're fine.
Made with galvanized metal shades and weatherproof molded rubber sockets, each string is 50 feet long and has ten 25-40 watt sockets (bulbs not included). We recommend a dimmer as well, because the light can be very bright.
Martha Stewart used to sell these in her catalog (RIP) and now Smith & Hawken seem to be the only ones with them ($135 on sale). We've also found them at Kmart under the Martha Stewart brand, but they're not online. If you live near one, do check first.