Both my 'Urban' and 'Wild' PSKs contain a WHITBY FIREFLY LITE KEYRING KNIFE. These are well built small lock knives with a 2 1/4" stainless drop point blade and a built-in red LED light beam. They fit in a tobacco tin easily (put the recessed button for the LED against the outside to avoid accidental use)
and whilst they're not of 'bench made' quality they are far superior to the cheap blades included in ready made psks.

As for tarps I've always used small pebbles - they have been storng enough to turn a plastic exposure bag into an eight handle stretcher for a full grown man. <img src="images/graemlins/cool.gif" alt="" />

Hope this helps.