"good for a while" is incompatible with "anonymous" : which means there's no account that could be linked back to you (think how 4chan is used).
Also it tends to be made illegal for obvious reasons (even if in practice, everyone but the most careful user eventually gets identified by their IP, the logs of which Web servers are legally obligated to keep in most states).
Otherwise, if you actually meant pseudonymous payments, well, Flattr actually tried to do it. Flattr 1.0 basically died in the 2012-2013 Twitter APIpocalypse, while Flattr 2.0 never managed to get enough reach, unlike the Silicon Valley backed, new competitor, Patreon.
Also it tends to be made illegal for obvious reasons (even if in practice, everyone but the most careful user eventually gets identified by their IP, the logs of which Web servers are legally obligated to keep in most states).
Otherwise, if you actually meant pseudonymous payments, well, Flattr actually tried to do it. Flattr 1.0 basically died in the 2012-2013 Twitter APIpocalypse, while Flattr 2.0 never managed to get enough reach, unlike the Silicon Valley backed, new competitor, Patreon.