2 of 5 active text field

I just found one ;)

With the following Add-on enabled, you can press CtrlR to enter a 'new name' for the active object. In order to speed up the process you can hit Return and O to confirm afterwards:

enter image description here Click to enlarge

viewport-rename.py

import bpy
import re

bl_info = {
    "name": "Viewport Rename",
    "author": "poor",
    "version": (0, 2),
    "blender": (2, 77, 0),
    "location": "3D View > Ctrl+R",
    "category": "3D View"
}

class ViewportRenameOperator(bpy.types.Operator):
    """Rename Objects in 3d View"""
    bl_idname = "view3d.viewport_rename"
    bl_label = "Viewport Rename"
    bl_options = {'REGISTER', 'UNDO'}
    type = bpy.props.StringProperty()

    @classmethod
    def poll(cls, context):
        return (bool(context.selected_objects))

    def execute(self, context):
        scn = context.scene
        user_input = self.type
        reverse = False
        if user_input.endswith("#r"):
            reverse = True
            user_input = user_input[:-1]

        suff = re.findall("#+$", user_input)
        if user_input and suff:
            number = ('%0'+str(len(suff[0]))+'d', len(suff[0]))
            real_name = re.sub("#", '', user_input)           

            objs = context.selected_objects[::-1] if reverse else context.selected_objects
            names_before = [n.name for n in objs]
            for c, o in enumerate(objs, start=1):
                o.name = (real_name + (number[0] % c))
            self.report({'INFO'}, "Renamed {}".format(", ".join(names_before)))
            return {'FINISHED'}

        elif user_input:
            old_name = context.active_object.name
            context.active_object.name = user_input
            self.report({'INFO'}, "{} renamed to {}".format(old_name, user_input))
            return {'FINISHED'}

        else:
            self.report({'INFO'}, "No input, operation cancelled")
            return {'CANCELLED'}

    def invoke(self, context, event):
        wm = context.window_manager
        self.type = context.active_object.name
        #return wm.invoke_popup(self, width=400, height=200)
        return wm.invoke_props_dialog(self)

    def draw(self, context):
        row = self.layout
        row.prop(self, "type", text="New name")


# ------------------------------------------------------------------------
#    register and unregister functions
# ------------------------------------------------------------------------

addon_keymaps = []

def register():
    bpy.utils.register_module(__name__)

    # handle the keymap
    wm = bpy.context.window_manager
    kc = wm.keyconfigs.addon
    if kc:
        km = wm.keyconfigs.addon.keymaps.new(name='3D View', space_type='VIEW_3D')
        kmi = km.keymap_items.new(ViewportRenameOperator.bl_idname, type='R', value='PRESS', ctrl=True)
        addon_keymaps.append((km, kmi))

def unregister():

    for km, kmi in addon_keymaps:
        km.keymap_items.remove(kmi)
    addon_keymaps.clear()

    bpy.utils.unregister_module(__name__)
    del bpy.types.Scene.viewport_rename

if __name__ == "__main__":
    register()

The Add-on also allows to batch rename all objects in the current selection. The suffix is determined by the given number of hash characters at the end of the string. You can simply type Cube-### to get 'Cube-001', 'Cube-002' and 'Cube-003' as well as Cube-###r to get a reversed list:

enter image description here Click to enlarge