I'm not sure, I think someone made a thread about this before. If so, please forward me to it. :-)

Which items must be absolutely waterproofed in a hiking/SAR pack? I just bought some assorted Aloksaks and they look great, but the only item that really belongs in such a bag is toilet paper. Other items still get adequate protection from the backpack (water resistant). FAK is in it's own nylon pouch, also water resistant.

Any ideas?

My larger survival kit equipment is devided into several modules. All of them are put into ziplocks. IMO they are waterproof enough.

If you don't want to do that, I would at least waterproof you shelter/clothing, FAK and your FSK.

-Matches, lighter, flints if your lighter takes them
-Records, be they hard copy, magnetic or optical, including maps (more a BOB item)
-Socks, at least some of them, your main thermal layer
-depending on the packaging, most 1st aid items, all meds
-batteries, all electronics that aren't specifically listed as waterPROOF (if it's just water resistant, it might need to be bagged)
-certain food items - a soggy brew kit is a kick in the teeth
-stoves, most solid fuels
-sleeping bag (try drying that sucker if you need it when it's wet)

At least, in my experince, that's why needs to be waterproofed.

Add to Ironraven's list, the first aid kit.

My kits are all in groups and all within separate 6 mil zip-locks available in various sizes through www.royalbag.com . Not only do the zip-locks keep items dry, they also keep items sorted into groups. FAK, fire starting, food gathering, tools, water treatment, directional and signaling, etc. IMHO heavy zip-locks are a very convenient and efficient way to keep small to medium size kits of any type well organized and dry.

exactly what I said

electronics are in tupperware
sleeping bag is in a garbage bag
food in a stuff sac
and everything in the pack sits inside a HD garbage bag

For small items i.e matches, tinder, etc. I so a vacuum sealer guy. You can include a ziplock bag so that after you open the sealed bag you can reseal it somewhat. for larger items like sleeping bags the (waterproof) bags available really won't handle being submerged for an extended period, but what are the odds? They will do well for you providing you give them some shelter from the elements. I went to Ft. Lewis WA. with stuff I thought was waterproof, and learned you can't just leave them out in the weather.