Using a BrowserView as a traversable adapter utility in Plone

First off, you'll have to add this in one of your own Plone products. I will not go through creating a product in this tutorial.
Next, create a few files. Remember you can customize these to your liking. I will call this BrowserView "tool."

tool.py
interfaces.py

In the tool.py file do something like this,

from zope.interface import implements
from zope.component import getMultiAdapter
from plone.memoize.view import memoize, memoize_contextless

from Acquisition import aq_inner
from Products.CMFCore.utils import getToolByName
from Products.Five.browser import BrowserView

from interfaces import ITool

class Tool(BrowserView): 

  implements(IUWOshTools)

  @memoize_contextless
  def hello_world(self):
    return "Hello, World!"

Now in interfaces.py do something like this,

from zope.interface import Interface

class ITool(Interface):
  def hello_world(self):
    pass

In the interfaces.py file you'll need to declare each method you'll create in the Tool BrowserView

Now add this to your configure.zcml

<browser:page
  name="tool"
  for="*"
  permission="zope2.View"
  class=".tool.Tool"
  allowed_interface=".interfaces.ITool"
  />

<!-- We need to make the request annotatable for this to work -->
  <class class="ZPublisher.BaseRequest.BaseRequest">
    <implements interface="zope.annotation.interfaces.IAttributeAnnotatable" />
  </class>

Now in a tal expression you can do things like this,

here/@@tool/hello_world
python: here.restrictedTraverse("@@tool").hello_world()

Or in code you can do something like this,

from zope.component import getMultiAdapter

tool = getMultiAdapter((self.context, self.request), name=u'tool')

and you're done. SWEET!