Nope, it's not necessary to have domains and hosting to test these plugins.
You can install own LAMP Server if you are on Linux, or use XAMPP / WAMP in Windows. In that case use your local server by providing *localhost at your browser.
Well, which plugin you are looking for..??
They are extremely easy.
For Like Plugin : You just need to create a HTML Page and put the piece of code there...
Code:
<html>
<head>
<title>My Great Web page</title>
</head>
<body>
<iframe src="*www.facebook.com/plugins/like.php?href=YOUR_URL"
scrolling="no" frameborder="0"
style="border:none; width:450px; height:80px"></iframe>
</body>
</html>
Now you just need to replace the YOUR_URL with the Page URL you want people to like...
For Eg. in my case I did...
Code:
<html>
<head>
<title>My Great Web page</title>
</head>
<body>
<iframe src="*www.facebook.com/plugins/like.php?href=*www.facebook.com/LGP500"
scrolling="no" frameborder="0"
style="border:none; width:450px; height:80px"></iframe>
</body>
</html>
Anyway check out *developers.facebook.com/docs/guides/web/. The doc is extremely easy to get going, but you need basic HTML Knowledge to understand how to implement.