Simple Plugin/Hack example?

[Assim]

Hello everybody,

I've got experience in PHP and all the other web technologies for making a hack/plugin, I've read the vB manual and some other threads in here, but I want a simple hack example using templates and plugins.

Give me an example of a plugin code that takes a value from the database table, assigns it to a PHP variable, and then let that value to be displayed in the template.

I know to know the best practice to put all this together, you can give me this example or any other simple example from you.

Thanks in advance.