The Perth Mint in Australia are releasing a series of ten coins featuring (five of each) captains and starships from the various Star Trek series.
The coins are 99.9% pure silver, and while collectible, are also legal tender in Tuvalu, in case you happen to be down that way. The biggest downside is the price: At the AUD to USD exchange rate today, they are running approximately $82 US Dollars each, a pretty hefty markup given that silver is currently trading at $16.51 per ounce.
Either way, they are worth a look if you are a serious Star Trek collector or aficionado.
Reference URL: http://www.perthmint.com.au/catalogue/star-trek-the-original-series.aspx