Just few comments on above notwa's method :)

(Oh and transform string concatenation with + to a string.Format)
Also made a small fix to externaltoolmanager

BizHawk.Client.ApiHawk/Classes/ExternalToolManager.cs

@@ -37,7 +37,10 @@ namespace BizHawk.Client.ApiHawk
 			}
 			directoryMonitor = new FileSystemWatcher(Global.Config.PathEntries["Global", "External Tools"].Path, "*.dll");
 			directoryMonitor.IncludeSubdirectories = false;
-			directoryMonitor.Created += DirectoryMonitor_Created;
+			directoryMonitor.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName;
+			directoryMonitor.Filter = "*.dll";
+			directoryMonitor.Created += new FileSystemEventHandler(DirectoryMonitor_Created);
+			directoryMonitor.EnableRaisingEvents = true;
 
 			BuildToolStrip();
 		}

BizHawk.Client.Common/tools/Watch/SeparatorWatch.cs

@@ -74,7 +74,12 @@ namespace BizHawk.Client.Common
 		{
 			get { return string.Empty; }
 		}
-		
+
+		/// <summary>
+		/// TTransform the current instance into a displayable (short representation) string
+		/// It's used by the "Display on screen" option in the RamWatch window
+		/// </summary>
+		/// <returns>A well formatted string representation</returns>
 		public override string ToDisplayString()
 		{
 			return "----";

BizHawk.Client.Common/tools/Watch/Watch.cs

@@ -567,9 +567,14 @@ namespace BizHawk.Client.Common
 				);
 		}
 
+		/// <summary>
+		/// Transform the current instance into a displayable (short representation) string
+		/// It's used by the "Display on screen" option in the RamWatch window
+		/// </summary>
+		/// <returns>A well formatted string representation</returns>
 		public virtual string ToDisplayString()
 		{
-			return Notes + ": " + ValueString;
+			return string.Format("{0}: {1}", Notes, ValueString);
 		}
 
 		#endregion