Summary by expiry period. For full conditions and links, please refer to the first post (or the linked thread for US-based FFPs).
No expiry for all
FM Shanghai Airlines Crane Club
KE Korean (miles earned to 30 June 2008)
OZ Asiana (miles earned to 30 September 2008)
TP TAP Victoria (provided pay fees each 3 years)
No expiry for some
AF/KL Air France/KLM Flying Blue - elite status
LH/LO/LX/OS/OU/JP Miles and More - HON, SEN, FTL and holders of LH credit cards issued anywhere
MH - Platinum status
NH ANA Mileage Club - Diamond status
NZ Air New Zealand Airpoints - Gold Elite, Gold
No expiry with activity in last 3 years
AC Air Canada Aeroplan (until 1 July 2007)
BA British Airways Executive Club
DL Delta Airlines Sky Miles - will change to 2 calendar years 31 December 2006
HA Hawaiian Airlines Hawaiian Miles
JK Spanair (each 31 March)
NW Northwest World Perks
OK CSA Czech Airlines OK Plus
QF Qantas Frequent Flyer (monthly)
VS Virgin Atlantic Flying Club
YX Midwest Miles
No expiry with flight activity in last 3 years
SU Aeroflot xxxx (also SU-branded credit card earning extends expiry)
No expiry with activity in last x period (under 3 years)
F9 Frontier Early Returns - 31 December of 2 calendar years after earning
AS Alaska Airlines Mileage Plan - 2 years
BD BMI Diamond Club - 2 years
DL Delta Airlines Sky Miles - 2 years from 31 December 2006
AF/KL Air France/KLM Flying Blue - 20 months after last status earning (non-elites)
US US Airways Dividend Miles - 18 months, or 36 months upon payment of fee
AA American Airlines AAdvantage - 18 months
CO Continental Airlines One Pass - 18 months
UA United Airlines Mileage Plus - 18 months
AC Air Canada Aeroplan - 12 months from 1 July 2007
additionally miles expire 7 years after earning from 1 January 2007, can be extended for further 7 years upon payment of fee
Spirit Free Spirit - 6 months(!), and activity is defined as earning 2000 miles
Expires in 10 years
GF Gulf Air Redemption Units expire after 10 years
Expires in 7 years
AC Air Canada Aeroplan from 1 January 2007, can be extended for further 7 years upon payment of fee
additionally expires after no activity for 12 months
OZ Asiana elite status members (miles earned from 1 October 2008)
Expires in 5 years
KE Korean (miles earned from 30 June 2008)
OZ Asiana non-elite status members (miles earned from 1 October 2008)
SK SAS Eurobonus
Expires in 4+ years
NZ Air New Zealand Airpoints - other than Gold Elite and Gold
QR Qatar Privilege Club
Expires in 4 years
Expires in 3+ years
EK Emirates Skywards - end of month of birthday that is 3 years after mileage credit
MH Malaysian Enrich - other than Platinum, can be extended once for 12 months upon payment of a fee
RG Varig Smiles
SA South African Voyager (can be rolled over with sufficient tier miles or SA-branded credit card spend)
TG Thai Royal Orchid Plus
Expires in 3 years
CX Cathay Pacific Asiamiles
LH/LO/LX/OS/OU/JP Miles and More - general members
SQ Singapore Airlines Kris Flyer - extendable for 6-12 months upon payment of a fee.
TK Turkish Airlines Miles & Smiles
TP TAP Victoria - extendable indefinitely for 3 years at a time upon payment of a fee.
Expires in 2+ years
NH ANA Diamond - other than Diamond
Expires in 2 years
CA Air China Phoenix Miles
WN Southwest Rapid Rewards
Expires in 1+ years
VX Virgin America eleVAte - 18 months
Expires in 1 year
Airtran A+
go! Miles
JetBlue True Blue (unless have the right affiliated credit card)