Blessed be God. 
Blessed be His Holy Name. 
Blessed be Jesus Christ, true God and true Man. 
Blessed be the Name of Jesus.
Blessed be His Most Sacred Heart.
Blessed be His Most Precious Blood.
Blessed be Jesus in the Most Holy Sacrament of the Altar.
Blessed be the Holy Spirit, the Paraclete.
Blessed be the great Mother of God, Mary most Holy.
Blessed be her Holy and Immaculate Conception.
Blessed be her Glorious Assumption.
Blessed be the name of Mary, Virgin and Mother.
Blessed be St. Joseph, her most chaste spouse.
Blessed be God in His Angels and in His Saints. Amen.

May the heart of Jesus, in the Most Blessed Sacrament, be praised, adored, and loved with grateful affection, at every moment, in all the tabernacles of the world, even to the end of time. Amen

—from Catholic Prayers.com    Originally written in 1797 by a Jesuit priest in recognition of rampant blashemy and profanity.  Say this prayer while in Eucharistic adoration or as a personal meditation.

We beseech you, O Lord, let the power of the Holy Spirit be always with us; let it mercifully purify our hearts, and safeguard us from all harm. Grant this through Christ our Lord, Amen.

May the Comforter, Who proceeds from You, enlighten our minds, we beseech you, O Lord, and guide us, as Your Son has promised, into all truth. We ask this through Christ, our Lord, Amen.

Holy Spirit, Sweet guest of My Soul, Abide In Me
and Grant That I May Ever abide in Thee.

"Angel of God, my guardian dear, to whom God's love entrusts me here, ever this day be at my side, to light and guard, to rule and guide.  Amen"

"St. Michael, the Archangel, defend in battle.  Be our protection against the wickedness and snares of the devil.  And do thou, oh Prince of the Heavenly Host, by the Power of God, cast into hell Satan and all the evil spirits who prowl throughout the world seeking the ruin of souls.   Amen"

"Watch thou O Lord with those who wake, or watch, or weep tonite and give Thine angels charge over those who sleep.  Tend thy sick ones, O Lord Christ, Rest Thy weary ones, Bless Thy dying ones, Soothe Thy suffering ones, Pity Thine afflicted ones and Shield Thy joyous one. All for Thy loves sake."   Amen 
From St. Augustine