Fourth in the Vegas Vamps series by Erin McCarthy...
Again... I have issues... but I think this is the last one available (at least right now, no idea if there's more planned) so I should be able to stay in genres I enjoy more than this one.
This one is mostly about Gwenna (sister of Mr. Pres) and Nate (mortal cop) and the two of them meeting and falling madly in love within days and all that ridiculousness. There's also some business with a "slayer e-mail ring".
edited August 2008 to add: This falls under example 1 in the Romance Disclaimer