Here's a great prayer for advent taken from the Valley of Vision:
O SOURCE OF ALL GOOD,
What shall I render to thee for the gift of gifts,
thine own dear Son, begotten, not created,
my Redeemer, proxy, surety, substitute,
his self-emptying incomprehensible,
his infinity of love beyond the heart’s grasp.
Herein is wonder of wonders:
he came below to raise me above,
was born like me that I might become like him.
Herein is love;
when I cannot rise to him he draws near on
wings of grace,
to raise me to himself.
Herein is power;
when Deity and humanity were infinitely apart
he united them in indissoluble unity,
the uncreated and the created.
Herein is wisdom;
when I was undone, with no will to return to him,
and no intellect to devise recovery,
he came, God-incarnate, to save me
to the uttermost,
as man to die my death,
to shed satisfying blood on my behalf,
to work out a perfect righteousness for me.
O God, take me in spirit to the watchful shepherds,
and enlarge my mind;
let me hear good tidings of great joy,
and hearing, believe, rejoice, praise, adore,
my conscience bathed in an ocean of repose,
my eyes uplifted to a reconciled Father;
place me with ox, ass, camel, goat,
to look with them upon my Redeemer’s face,
and in him account myself delivered from sin;
let me with Simeon clasp the new-born child
to my heart,
embrace him with undying faith,
exulting that he is mine and I am his.
In him thou hast given me so much
that heaven can give no more.
Used with permission from banneroftruth.org
Taken from the Valley of Vision - an excellent collection of prayers - you can buy it here