If you have heard about HelloBar, ViperBar is quite similar to it but there are no limitations you can add email opt-in box, feedburner email subscription form and anything which you think will look nice on the ViperBar.
Even WSJ best-selling author Steve Farber is using ViperBar on his website.
By placing email opt-in box right in to the ViperBar you are doing two great things first you are not annoying your visitors second You are winning number game, yeah number of email subscribers will start to increase at an exceptional rate. The only thing you have to do is to Install ViperBar WordPress Plugin. It’ll take less than 30 seconds.
If still you are not impressed, Read all the features available on about page and most important thing ViperBar is free.