MB Creation

Popup a message on your WordPress blog is now very easy.
If you want to promote your brand new newsletter functionnality, display advertising on your homepage or get more Facebook fans you can use Simple Popup Manager to popup a message all over your content in a lovely “lightbox effect”. You can customize your message using a WP editor and of course specify the width and the height of the message box. You can limit the display of the message on either session or days basis.
<ul>
<li>Choose wether the popup will be displayed only on homepage or on every page</li>
<li>Set size, width and threshold of the popup (you can disable mobile)</li>
<li>Customize background-color and opacity</li>
<li>Popup content is just a normal WordPress editor (you can use shortcode)</li>
</ul>

Simple Popup Manager

Simple Popup Manager allows you to easily popup and display a simple message box on your WordPress front page.

Valice

Banner alerts are custom alerts to notify your website visitors of promotions, alerts, events, etc. These display at the top of the website until they are dismissed by the visitor. Any new visitor who has not been to the website will see these until they are dismissed.
Banner alerts are configured just like a post or page with support for title, content, and excerpt. The plugin settings allow you to define which parts of the alert to display and whether or not to link to the full post. You can run more than one alert at a time and activate or deactivate as needed.
This plugin is ideal for:
<ul>
<li>Important operational changes</li>
<li>Technical notices</li>
<li>Time-sensitive appeals for donation or action</li>
<li>Terms or agreement changes</li>
<li>Privacy notice acknowledgements</li>
<li>Service outages or maintenance messages</li>
<li>Special offers or promotions</li>
</ul>

Banner Alerts

Provides an easy interface for creating and displaying alerts or notices as a banner on a website

Simple Popup Manager vs Banner Alerts