There's a gem for that!

src/scripts/rubygems.coffee

@@ -0,0 +1,14 @@
+# Find a rubygem from rubygems.org
+#
+# hubot <there's a gem for> that - Returns a link to a gem on rubygems.org
+#
+
+module.exports = (robot) ->
+  robot.respond /there's a gem for (.*)/i, (msg) ->
+    search = escape(msg.match[1])
+    msg.http('https://rubygems.org/api/v1/search.json')
+      .query(query: search)
+      .get() (err, res, body) ->
+        results = JSON.parse(body)
+        result = results[0]
+        msg.send "https://rubygems.org/gems/#{result.name}"