Building on what’s said above–indulgences are still available if you’re interested in getting them. There are two types: plenary and partial. The partial indulgences traditionally had a number of days attached–these were actually an outgrowth of the days of public penance, when one might have to do public penance for a year (or more), depending on how heinous the misdeeds.
Indulgences don’t involve exchange of money, but particular acts–for example: “A partial indulgence is granted to the faithful who use Sacred Scripture for spiritual reading with the veneration due the word of God. A plenary indulgence is granted if the reading continues for at least one half hour.” (Enchiridion Indulgentarium , 1968. No. 50). Others involve making pilgrimages and offering particular prayers there.
A person can get the indulgence for himself or on behalf of one of the souls in Purgatory (who are, as noted above, not being afforded a second chance at salvation, but rather are saved, but not quite ready to enter the full joy of heaven. Being a person who likes little homely illustrations: I call Purgatory the mudroom of the mansion which is Heaven (not perfect, but the point is Purgatory is part of Heaven–some people enter through the front door (directly), others through the mudroom (purgatory first), but none of those will end up in Hell.