A Ring of Stealth will keep monsters from noticing you. A +12 ring will reduce your stealth range to 2 even in lit areas as long as you are wearing leather armor, scale mail, or no armor. See the page on Stealth for more information.
A Staff of Blinking might be the lynchpin of a Maneuverability Build, but it's important to a stealthy adventurer, too. Blinking draws no extra attention to you but it lets you cross wide, vulnerable spaces quickly. You can blink in, stab, and blink away if things go south.
A Ring of Clairvoyance will help you decide whether to go through a door or trample foliage. This is one of the few builds that benefits significantly from enchanting a Ring of Clairvoyance.
A Staff of Entrancement will force an enemy to try to notice you again. If you have a highly enchanted ring of stealth, and especially if you have blinking, too, you can repeatedly land critical hits.
A Staff of Conjuration will also allow you to put some distance between you and monsters hunting for you, allowing you to hide from them again.
A Staff of Poison does not alert enemies to your presence, although it does wake up sleepers.