And I'll start with my own easy-as-crap tricks. I've trained admins from very little base knowledge, so some of this might be a no-brainer to more senior admins.
DNS and DHCP
Easy enough to find both at once, and is a good jumping-off point:
Start, Run, CMD, ipconfig/all on your workstation. This gives us the DHCP server, the DNS servers, and the IP address for our switch (the Default Gateway).
We also get our domain, and maybe the subnet mask will imply the size of your network to some degree. Ping-a on any of these addresses will also provide some insights into the naming scheme which might help a bit too.
Finding Servers
Once you have DHCP, you can add the server to that snapin (Admin Tools, DHCP). With a bit of luck the servers will have DHCP reservations in the low or high end. Regardless, even if servers aren't always named helpfully, they tend to at least have some indicator that they are servers in the name.
Finding File Servers
Hopefully you have the standard file servers mapped to your account, and can just hit up "My Computer" to find those names. Even so, it wouldn't hurt too badly to start up a Remote Desktops MMC, add in all the servers you've found, and log in once. It'll at least add your profile to the machines, and while you're at it? Right-click on "My Computer" in each one, hit Manage, and open the "Shared Folders/Shares" folder. Anything that doesn't end in a $ sign is, to some degree or another, a public share. Even on the domain controllers. Never underestimate the poor choices necessity can force.
Finding IIS Web Servers and SQL Servers
While we're in the Computer Management console, open up "Service sand Applications." If you have "Internet Information Services (IIS) Manager", you've got a web server. If you have "SQL Server Configuration Manager," you've got an SQL Server. The IIS might be for Exchange, the SQL Server might be for WSUS or Backup Exec or whatever (before long your web browser will "need" one, for no apparent reason), but you've got them.
Alright, that's all the time I have for documentation (aka forum posts) today.