One tool kit for multiple bikes?

A difficult balance of liking to be prepared and trying not to carry too much crap around for me.

Road kit - actual allen keys and mini screwdriver (decided they were pretty much as compact and way more useful), sticky patch kit (the tiny park tools one), chalk, wad of gaffa, spare link and key for the crappy lock that ties my saddle on (don't trust London bike theives) all go into a small old puncture repair box, with a standard chain tool disassembled and taped to the box and levers held on with elastic band.
This sounds big but is only 10x5x3cm, solves almost every problem and can go in pocket or bag.
Small pump on frame or in pocket. Tube with me if going with other people, but if I'm on my own I'll patch it.

Other bike requires more tools to undo everything, so I just chuck the road box into a saddle bag with a resident multitool in it, which usually goes in a backpack anyway.

I'm planning on getting creative with an old innertube and making some custom cases for things that need holding together or keeping dry...I'm time rich - cash poor at the moment!

I did the while EPMS thing for a while.. ditched it when I tore a tube attempting to pump a swap in the rain.

I rock a CO2 shot, a tube, tire levers, two Allen wrenches, and a phone (in a ziplock bag) in pocket. Keep my ID, a credit card, and $20 together tucked in my shorts.
Conti gatorskins give me a little confidence that I'll only lose one tire.

Don't fall for top of the line waterproof things for phones.. I had a ziplock keep my brand new HTC one safe in torrential, severe severe severe thunderstorm.

For some reason I feel compelled to share my habits regarding this with the community!

Road - small seat pack with a tube, levers, multitool and sometimes a repair kit. A Topeak Micro Rocket pump squeezes in there as well. I'm not a fan of those look-like-you-could-fit-a-dog-in-them saddle packs which practically drag on the rear wheel.

Commute - tube (Schraeder), levers, multitool and pump (a different one) wrapped in a supermarket plastic bag, which wears out and gets replaced once a month or so, inside my pannier. Actually tucked into the mesh bottle holder within the main pocket - it seems to fit in there just right.

MTB - don't do nearly enough MTBing but will have the usual in a small backpack.

I save up punctured inners and do a mass repair/chuck out every so often, and feel very worthy about it too. Also lights - commuter has decent ones permanently wired in, but I try and remember to take smaller flashers with me on the roadie. Reading this back I think I a) need to get out more and b) should try and be more organised!

Weirdly interested to read others' responses as well, goodness cycling makes you anal doesn't it?

I tend to pick up the cheap saddle bags whenever they're on offer in Lidl/Aldi and stick relevant MTB/road tools in each.

On the winter/wet bike (rigid MTB, Schraeder valve) I put tube, levers and a puncture repair box containing 4 & 5mm allen keys, mini screwdrivers and patches in my rucksack.

A Topeak seat pack lives on the road bike.

The TT bike has an inner tube and 2 levers taped to the seat post.

I try not to swap stuff across - each bike has a pump, as I've forgotten to carry one before and worry I could get stuck without one.

Swap them over here. That said most of my rides are shorter these days plus I'm generally near civilization too!

But road stuff in the jersey pockets or when mtbing in a small pack (hydro without the bladder).

I'm always swapping between bikes and I have been using this for the past few months:
http://road.cc/content/review/81489-lezyne-phone-caddy

It takes up a rear pocket. You'd only get one inner tube in there. But I have a multi tool, tyre levers, patches, valve extender, chain link etc in there, and a mini pump fits on the side. It's hard wearing too.

Check out the Lezyne range. They have loads of other options too.

I have a tool bottle too, which is treat for most situations, but for longer rides where I want my bottle cage for water, it all goes in a small saddlebag.
I'm pretty minimilast though as I used to be a messenger, pretty much the c02 , tyre levers and tube persuasion. But usually a small repair kit just in case the a 2nd puncture occurs and a small multitool for everything else.
Very tempted by a frame bag or something similar though. As would suit my touring bike as well as my commuting bike a bit better