ive made a funny program using eval()...
its quite cool, i dont know how handy it might be, but here it is none the less...
var the_code = window.document.form_1.textarea_1.value;
<h1>write some code!</h1>
<textarea name="textarea_1" rows=10 cols=40>
<form onSubmit="return false;">
<input type="submit" value="submit your code" onClick="submitCode();">
very simple stuff, but for those of you who are unfamilir with eval, its pretty cool, huh?