If you aren't using prestige classes, rogue levels might be nice. Sneak attacks do a lot for archery, especially if you have access to greater invisibility or blink. UMD can help you with that, tumble can substitute for close combat shot much of the time, and stealth is always nice to have. Monk levels could be fun, too, as very nice things happen to your saving throws, and it's nice to be able to kick someone in the head without dropping your bow.
If you don't want to multiclass, there are several options for feats. The mounted combat line (including mounted archery and improved mounted archery) can greatly expand your maneuverability in more open combats, especially if you can aquire a flying mount. Combat expertise can help keep you alive, as can the various saving throw feats. For that matter, ae you sure that you have all the archery feats? Don't miss Improved Rapid Shot in complete warrior, it eliminates the -2 penalty when using rapid shot.