The biggest and most obvious imitation of tipjar is Paypal,
which accepts credit cards, sends lots of junk mail, and has
been absorbed into auction supersite ebay.
As if you need
e-bay to have an online auction. You don't. Just describe your
goods for sale on a web page and wait for your customers to
google for what they are looking for.
Amazon and Yahoo have both developed their independent payment systems.
They're not that difficult to set up.
The dotGNU cashbox system will allow any merchant to
track "in-store credit" for their customers.
TipJar continues to be the only system that:
does not charge a percentage from either the
giver or the receiver of a tipjar transaction
does not share customer e-mail addresses with mass marketers
uses only collected funds, preventing "chargebacks" from
occuring with tipjar transactions
has anonymity features built in to allow anonymous giving
allows definition of non-email-address nicknames, and
definition of "minimum acceptable tip", in effect
creating a sender-pays messaging system that has been
operating since 1996
... more later ...