MAJOR CRYPTOCOINS - Big market, high security
BTC Bitcoin - first, strongest, most accepted, most mined, high volume market, a true currency
LTC Litecoin - second only to BTC , faster than BTC, Smaller efficiency gap between GPUs and CPUs , ASIC-hostile
NMC Namecoin - merged mined with BTC, used for alternative p2p domain system
PPC PPcoin - Proof Of Stake [very innovative, low energy], compatibile with BTC miners
MINOR CRYPTOCOINS - Established, but small
NVC NovaCoin - scrypt hashing[like LTC], proof of stake [like PPC]
XPM PrimeCoin - mining PrimeCoin helps looking for prime numbers, instead of wasting energy. for now cpu-only.
DVC Devcoin - merged mined with BTC, 90% of generation goes to foundation, 10% to miners
FTC FeatherCoin - LTC clone with 4x more coins. starting diff 0
FRC Freicoin - 4.89% anual demurrage. for the first 3 years 80% block subsidy goes to foundation, 20% to miners.
TRC Terracoin - BTC clone, many diff algo updates, still abused.
CANDIDATE CRYPTOCOINS - Not stable yet, with some community support
IXC IxCoin - merged mined with BTC, BTC clone.
DGC DigitalCoin - LTC clone. 20 sec blocks. 0 starting diff + progresive reward.
MEC Megacoin - based on 8.2 code. 0 starting diff.
BQC BBQCoin - forgotten , now revived and active. faster version of LTC.
YAC YACoin - Yet Another altCoin. NovaCoin fork, with modified scrypt hashing
WDC Worldcoin - LTC clone. 15 sec blocks. 0 starting diff.
CNC CHNCoin - LTC clone, announced on chinese forum first.0 starting diff
BTB BitBar - scarce, PoW + PoS[like PPC] scrypt. 0 starting diff + quick adjustment.
MNC Mincoin LTC - LTC clone, started with no binaries and 25000% reward blocks. 0 starting diff
PXC PhenixCoin - LTC clone. 1'000'000 coins premine.