You mean something like rev6.com? like their server stats?
well it's pretty easy to get those info.
just create a proxy which is between the client and the server and wait for the server list packet.
owh and you might want to send the get server list packet after like 5 seconds to get the up to date list
You have to take care of the silkroad security but you might want to use srProxy or some other proxy which already takes care of that and just connect with it to get the data.
btw in the server list packet you got all the data which rev6 also has, server id, name, an float which is 0 for empty and 1 for 100% full, and if the server is in check or online