i look for a particular plugin

Hi, i cannot find a plugin that allows to reserve shares, for example i need to let people click somewhere and reserve a share or a quota or more than one out of a total number, more on i need to have reserves in case someone at the last moment renounces, of course would be perfect if it could be made in an ordered way with a list showing who got there first and how many quotas took.
Anyone knows if some plugin like this exists?
Thank you in advance for your time
cheers.