Fridays in Lent can reap eternal benefits, either for yourself or for a loved one in purgatory, with a plenary indulgence available.
During the Fridays of Lent, you may obtain a plenary indulgence by reciting after Holy Communion the following prayer before a crucifix, or image of Christ crucified. The normal conditions for an indulgence also apply.
Read more:
The saints tell us what Purgatory is actually like
Prayer Before a Crucifix/Prayer to Christ Crucified.
Behold, O kind and most sweet Jesus, I cast myself upon my knees in thy sight, and with the most fervent desire of my soul, pray and beseech thee that thou wouldst impress upon my heart lively sentiments of faith, hope, and charity, with true contrition for my sins and a firm purpose of amendment; while with deep affection and grief of soul I ponder within myself and mentally contemplate thy five wounds, having before my eyes the words which David the prophet put on thy lips concerning thee: “My hands and my feet they have pierced, they have numbered all my bones” (Ps 21, 17-18). Amen.
See here for the conditions in order to receive a plenary indulgence (or any indulgence):
Read more:
A Primer on Indulgences, Part 1
Read more:
A Primer on Indulgences, Part 2