Janis Elsts

Normally when you login to your blog WordPress will create a session cookie that is used to authenticate you. If someone was to steal the cookie they would be able to use it to get full access to your blog without having to know your password. This plugin prevents that from happening – it makes the cookie specific to your IP address, so it won’t be usable from a different computer.
Use this plugin if you have a static IP. If you have a dynamic IP address and it changes often you will get logged out frequently.
A bit more info can be obtained from the <a href="http://w-shadow.com/blog/2008/07/12/safer-cookies-plugin-for-wordpress/" title="Safer Cookies homepage" rel="nofollow ugc">Safer Cookies homepage</a>

Safer Cookies

Ties the WP session cookie to your IP address so that it can't be used to get access to you blog from another computer.

ruudkok

Don’t keep logging in to your WordPress admin panel over and over again. Install this plugin to remain logged in to your blog for up to a year (unless you log out manually).

WP Keep Me Logged In

This plugin will increase the session time of your WordPress login cookie to 1 year. That way you won't have to login over and over again.

Safer Cookies vs WP Keep Me Logged In