SQL & PL/SQL

Does anyone know of a technique of storing information in memory while making this information available to other sessions (=users) ?

We are looking for methods to store a small predefined (about 100) number of values that can be accessed by other sessions very quickly while the values are modified very, very frequently.

Storing the information into a table does not really cut it due to the extreme high volume of transactions involved.
Basically we have a writer process that is adding information to a table but it also needs to update a set of counter variables which need to be continuously checked by other processes.

We have discarded global package variables and temporary tables as the values are not visible to other sessions.
Currently we are using database tables to store the information but the writes and reads on this table are to slow.

Help please,