An important part of scalability is testing. How do you know if it will scale if you don't test? But, sometimes you just want to do more of a quick performance test to see if anything is obviously wrong. I found a nice little tool called WBox1 recently that is pretty versatile.
It's a quick way to test a variety of things as follows. Summaries of all these items and command structure can be found on the tools web site.
Testing virtual domains - Interesting in that it allows you to fake a host file change
Stressing servers and apps - A little stress testing
Dumping data - Checking headers to pinpoint issues
Obtaining timing information per component - A breakdown of what's being downloaded per page
Basic usage - Similar to ping but for a web page
Web Page Size - Quick Answer to how big is that page?
So, as another handy tool in the System Administrators tools box, WBox might have a rightful place for you.
Wbox - http://hping.org/wbox/?ver=4