diff --git a/README.md b/README.md
index f5b6ae2..83ba1ae 100644
--- a/README.md
+++ b/README.md
@@ -7,6 +7,15 @@ A framework for building letsencrypt clients, forked from `letiny`.
   * browser WebCrypto (not implemented, but on the TODO)
   * any javascript implementation
 
+### These aren't the droids you're looking for
+
+This is a library / framework for building letsencrypt clients.
+You probably want one of these pre-built clients instead:
+
+  * `letsencrypt` (100% compatible with the official client)
+  * `letiny` (lightweight client)
+  * `letsencrypt-express` (automatic https for express)
+
 ## Usage:
 
 ```bash
diff --git a/example/challenge-store.js b/example/challenge-store.js
new file mode 100644
index 0000000..cae50e0
--- /dev/null
+++ b/example/challenge-store.js
@@ -0,0 +1,30 @@
+// Finally, you need an implementation of `challengeStore`:
+
+'use strict';
+
+// Note:
+// key is the xxxx part of `/.well-known/acme-challenge/xxxx`
+// value is what is needs to be return the the requesting server
+//
+// it is very common to store this is a directory as a file
+// (and you can totally do that if you want to, no big deal)
+// but that's super inefficient considering that you need it
+// for all of 500ms and there's no sense in that.
+
+
+var challengeCache = {};
+var challengeStore = {
+  set: function (hostname, key, value, cb) {
+    challengeCache[key] = value;
+    cb(null);
+  }
+, get: function (hostname, key, cb) {
+    cb(null, challengeCache[key]);
+  }
+, remove: function (hostname, key, cb) {
+    delete challengeCache[key];
+    cb(null);
+  }
+};
+
+module.exports = challengeStore;