The Rescue Insurance landscape seems to change daily, as clubs and insurers change their policies and offerings.
What you purchase depends mostly on where you are from and where you plan to go. Most national alpine clubs offer rescue insurance as part of, or as a supplement to the club dues. This is a good place to start looking.
The American Alpine Club offers global rescue insurance to its members. You will need to contact the AAC for details.
The French as Swiss Alpine Clubs also offer rescue insurance, but currently it appears to be limited to residents of those countries.
If you are climbing or skiing wholly
within Switzerland, you can subscribe to REGA. REGA rescue insurance
can be purchased in most Swiss post offices and costs 30 Swiss
Francs for the year for an individual. If your activities
are just within Switzerland, this is a good deal. Family subscriptions
are also possible. For non-Swiss it is valid only within Switzerland.
See http://www.rega.ch for more
information.
Similar to Rega, Air Glacier is another Swiss product. It is a good choice if you are climbing in the Zermatt area or Valais. Like Rega, it is limited to accidents or evacuations that occur within Switzerland. Air Glacier's website can be found at http://www.air-glaciers.ch You can sign up online for about 35 CHF per year.
The French Carte Neige is another option, but recent policy changes have made non-French enrollment difficult, requiring doctor's examination and translation.
Currently, one of the best options for Americans appears to be to join the UK Section of the Austrian Alpine Club. Anyone can join, regardless of residence, and the associated rescue insurance is valid worldwide (with a few exceptions, such as 8000-meter peaks, Greenland, the Arctic and Antarctic). Visit their website at http://www.aacuk.org.uk for more information.
British residents can also choose the Snowcard, which offers a range of coverage options. See www.snowcard.co.uk for more information.
Last, for short off-piste or touring trips to the Chamonix area, it is possible to easily and inexpensively purchase insurance when you buy your lift ticket.