diff -up dwm/config.def.h new/config.def.h
--- dwm/config.def.h	2008-10-23 17:35:39.000000000 +0200
+++ new/config.def.h	2008-10-23 17:49:42.000000000 +0200
@@ -69,6 +69,8 @@ static Key keys[] = {
 	{ MODKEY|ShiftMask,             XK_space,  togglefloating, {0} },
 	{ MODKEY,                       XK_0,      view,           {.ui = ~0 } },
 	{ MODKEY|ShiftMask,             XK_0,      tag,            {.ui = ~0 } },
+	{ MODKEY|ShiftMask,             XK_Left,   prevtag,        {0} },
+	{ MODKEY|ShiftMask,             XK_Right,  nexttag,        {0} },
 	TAGKEYS(                        XK_1,                      0)
 	TAGKEYS(                        XK_2,                      1)
 	TAGKEYS(                        XK_3,                      2)
diff -up dwm/dwm.c new/dwm.c
--- dwm/dwm.c	2008-10-23 17:35:39.000000000 +0200
+++ new/dwm.c	2008-10-23 17:47:42.000000000 +0200
@@ -168,7 +168,9 @@ static void mappingnotify(XEvent *e);
 static void maprequest(XEvent *e);
 static void monocle(void);
 static void movemouse(const Arg *arg);
+static void nexttag(const Arg *arg);
 static Client *nexttiled(Client *c);
+static void prevtag(const Arg *arg);
 static void propertynotify(XEvent *e);
 static void quit(const Arg *arg);
 static void resize(Client *c, int x, int y, int w, int h, Bool sizehints);
@@ -985,6 +987,21 @@ movemouse(const Arg *arg) {
 	XUngrabPointer(dpy, CurrentTime);
 }
 
+void
+nexttag(const Arg *arg) {
+        unsigned int mask;
+
+        if (tagset[seltags] >= (1 << (LENGTH(tags)-1)))
+                mask = 1 & TAGMASK;
+        else
+                mask = (tagset[seltags] << 1) & TAGMASK;
+
+        if(mask) {
+                tagset[seltags] = mask;
+                arrange();
+        }
+}
+
 Client *
 nexttiled(Client *c) {
 	for(; c && (c->isfloating || !ISVISIBLE(c)); c = c->next);
@@ -992,6 +1009,21 @@ nexttiled(Client *c) {
 }
 
 void
+prevtag(const Arg *arg) {
+        unsigned int mask;
+
+        if (tagset[seltags] <= 1)
+                mask = (1 << (LENGTH(tags) - 1)) & TAGMASK;
+        else
+                mask = (tagset[seltags] >> 1) & TAGMASK;
+
+        if(mask) {
+                tagset[seltags] = mask;
+                arrange();
+        }
+}
+
+void
 propertynotify(XEvent *e) {
 	Client *c;
 	Window trans;