This is a great contest that I've entered the past several summers. There are great books up for grabs as prizes, and it's a fun way to keep track of what you've been reading. You can check out exactly what you need to do to enter here.
Some of the books I'm planning to read for this are:
The Husband Maker by Karey White
Becoming Lady Lockwood by Jennifer Moore
Spell Check by Julie Wright
Tying the Knot by Josi Kilpack, Annette Lyon, Heather B. Moore and Julie Wright.
And more...of course!