Thanks to Brent Ozar for this one.
He describes how you could easily populate a list of (SQL) Servers by using one or a combination of these tools:
How to Survey Your Network for Servers
Put a row in the spreadsheet for every server you have – whether you’re in charge of it or not. We want to start with a good inventory of what we have, and there’s two good free tools to do it.
Microsoft Assessment and Planning Toolkit – it’s actually designed for licensing compliance, but it works great for building server inventories. It scans your network looking for whatever programs you pick, but just confine it to SQL Servers only.
Dell Discovery Wizard for SQL Server – it’s a GUI tool that pings all the servers in your network and tries to figure out if they’ve got SQL Server installed. If you’re in a small shop where your account has admin privileges in the domain, you might find a lot more servers than you expected.
SQL Power Doc – open source PowerShell scripts to discover, document, and diagnose your SQL Servers. I’m not gonna lie: this one is not for the faint of heart, but if you’re willing to get your hands dirty and deal with some manual work, the end result is a nice set of Excel spreadsheets.