CSI gives you a good selection of tools to detect evidence, and then tools to collect it properly. You don't want to damage evidence so it can't be used later on!

Detection Tools
These tools help you find evidence or examine it for clues to the crime.

Magnifying scope - for getting a close look at items in a crime scene
Ninhydrin - making fingerprints easier to see
Fingerprint brush poweder - clings to fingerprint oils to give them shape
UV light - helps to see details on an object
Sniffer - investigate gasses or fumes
Luminol - makes blood luminesce, or "light up"
IR Camera - detects heat signatures, showing warm objects up clearly.

Collection Tools
These tools help you gather up evidence in a safe way, so that the evidence can properly be evaluated back at the home office.

Swab - a cotton swab, great for taking cheek samples for DNA analysis
Gloves - use them to pick up objects so you don't get fingerprints on the evidence
Tweezers - yank out a suspect's hair for comparisons against other hairs you find.
Casting Plaster - good for casting tracks you find
Mikrosil - mold a wound to keep a permanent record of its exact shape
Adhesive lifting tape - good for those tiny items that are otherwise hard to get
Electrostatic dust print lifter - A good way to bring prints home for comparison

CSI Crime scene Investigation Walkthrough