Precision Glue Tips are now available for most glue bottles.
For Cyanoacrylate (crazy/super) glues
Metal tips in .025 and .027 sizes from Mission Models which fit commonly available cyanoacrylate (crazy/super) glues. The tips can be trimmed down and being made of metal are also easily bent, allowing them to get into most spaces you want to apply a fine bead of glue.
For Pva (white) Glues, Acrylic Paints, etc
Precision tips which fit most plastic glue bottles are available from art glitter through stamp and scrapbooking suppliers. These metal tips, designed for writing with glitter glues, twist on over the existing tip on standard plastic glue bottles but allow for a very thin stream application of glue, glitter, or acrylic medium/paint. Art glitter thoughtfully package them in a vial, which can be filled with water for cleaning, and include a stainless steel pin for temporary blocking of the fine point while it is attached to a glue bottle.
A similar tip is also available from several retailers attached to a small clear flexible plastic bottle. If you use the tip for paints you mix yourself, you may prefer to buy the tip with an empty fillable bottle, instead of buying just the tip to use on bottles with standard cone tops.