In the past I used to keep a tiny Swiss Army knife on my key chain but I no longer carry my keys with me all day long. I miss having the small blade available. So I looked for a small folding knife with a clip function.
The Gerber Paraframe Mini clearly is designed for this purpose. About the size of a tube of ChapStick this knife is always there but never gets in the way.
I think a great small knife for this purpose is the Gerber Paraframe Mini. I can clip it in my pocket and no really feel it there. But when something needs a cuttin' it's right there for me. At under $10 it's a great value.