Note: run programs you don't fully trust within an isolated VM.
Info about Bitcoin:
Bitcoin is a decentralised peer-to-peer crypto-currency. It's the most widely used crypto-currency.
Payments are absolute and one-way, they cannot be "charged back" or reversed once sent.
Anyone can confirm that a Bitcoin payment has been made, so scammers are easily outed.
Bitcoins are generated by solving math problems: https://en.bitcoin.it/wiki/FAQ#How_are_new_Bitcoins_created.3F
A Bitcoin address looks like this: 1GFR5BhAzTn8MpQ7JTybsMHYcKRguDx8dk (starts with a "1")
Info about Namecoin:
Namecoin is based on the same idea behind Bitcoin, but is used to register domains via P2P DNS. Currently the only TLD is .bit.
A Namecoin address looks like this: N3zTpjJw5gW87LGQtKfcyKvVBE9x49fqBV (starts with an "N", older addresses start with an "M")
Example: "xenforo.bit" will resolve to "10.1.33.7" when the transaction goes through and DNS updates. I'll transfer this domain to XF staff if requested.
Info about Litecoin:
Litecoin uses a different algorithm than Bitcoin which is easier to "mine" on a CPU, however, GPUs still mine it more efficiently. This currency might die out if its algorithm isn't changed to be GPU-hostile, since that is the backing behind its usefulness.
A Litecoin address looks like this: LNAfy3ggYttRV6UASSxi5KpTh64JmFdz2K (starts with an "L")
There are other currencies based on Bitcoin such as SolidCoin, Ixcoin, i0coin, RuCoin, Devcoin, Geistgeld, Liquidcoin, and so on. Different currencies generally have the same API, so I hope it's easy to implement them all at once.
It's also possible to generate an address with a recognisable name in it, for example with Vanitygen:
>vanitygen64.exe 1Kent Difficulty: 4476342 Pattern: 1Kent Address: 1Kent9NXn9hdW6Lk7DRxHAcJoP5LtBh3MZ Privkey: 5HvumNWjenksdKsbeEk4sVbU8zrMnULnZYBa4yXJtfjBEmX71Jy
Here's some info for PHP development with Bitcoin: https://en.bitcoin.it/wiki/PHP_developer_intro