another video, shows quick attach @1:20 : http://www.meyerproducts.com/Portals/0/Meyer/skid-steer/SkidSteer-EOU.jpg

This diagram illustrates the attachment process: http://www.youtube.com/watch?v=cd_Bn9z41Lk
the handles I mentioned can be seen in step 4

this link discusses the history of quick attach, and indicates that since 1994 all manufacturers adhere to the same geometry – there is also another dimensioned image:
http://www.bucketproinc.com/products/universalquickattachsystemqas.php

This video shows the clam shell bucket I mentioned, and how it is used: http://www.youtube.com/watch?v=7VE9eBktQQ4
they also are called “combo bucket” or “4-in-1 bucket”
image version: http://www.attachmentscjj.com/html/combination-fourinone-bucket.html

There are many companies that sell their own attachments to work with this system, this is just one example: http://www.everythingattachments.com/default.asp
Several companies have a track system that fits over the tires. You may want to reverse engineer this if you plan to have optional tracks in the future.

This thread discusses quick attach, but also provides a dimensioned image of the quick attach plate: http://www.tractorbynet.com/forums/attachments/113183-skid-steer-quick-connect-all.html

This video shows some of the functionality on a newer skid steer :
http://www.youtube.com/watch?v=49Yakrbo6hc
@ 0:20 they show the attach/detach process – on mine there are also two handles that lock down to hold the attachment in place, this appears to be automated on newer models though
@ 0:40 the red bar on the side is the safety bar that I mentioned to lock the bucket in place while you are under it
@ 1:02 you can see the cockpit with the two control sticks I mentioned

It’s very easy to get into, at least for coders, so not much cost in trying. Definitely add to your toolchain.

here is one of many low tech methods described on the internet:
http://www.caf.wvu.edu/~forage/library/forglvst/wvusite/hydrauli.htm

although a microcontroller solution could produce something much nicer that is part of the tractor control panel

weight data could even improve safety by letting the operator know (or auto correct center of mass) if they are in dangerous conditions based on a feed back loop using 3 axis accelerometers and bucket weight – my machine is a few years old so this may already be a common feature on some of the newer machines

When I have needed to build something in the past I often try to reverse engineer as much prior art as possible. Perhaps you have already done this, but if you have the access it may be informative to sketch or videotape a minimal tear down of some of the other newer machines (CAT, IR, John Deere, etc). If I lived closer I would gladly offer my CAT.

Some other useful items on my skid steer:
1. Auto bucket leveling regardless of the machine spatial state – maybe this is done with an accelerometer and a PID loop?
2. there is a safety bar that locks down and protects you if e.g. the hydraulics give out while I’m working under the bucket
3. a roll cage over the driver can be helpful since I’ve had a few dangerous moments with heavy bucket loads on the hilly terrain in my area – I suppose this could be a removable option on your design though
4. The controls are two joysticks/flight-sticks and I’ve found this a fairly intuitive design – one for movement and the other for attachment control
5. a full day in it and you will feel beat up – I wish my machine had air shocks or some other dampening system under the seat, maybe even ferrofluid/magnetic dampening? ferrofluid seems like it would be easy to make: oil carrier + Fe3O4

Since you are considering the next version of Lifetrac – I thought I would throw a few comments out on the things I (dis)like about the machine I have, I’m sure you’ve accumulated many more from active use of LifeTracI
Best of luck

I’m still learning how to use the machine to it’s full ability, but I have found the following attachments very helpful:
1. clam shell bucket (grading and other tasks are made much easier than a simple bucket)
2. set of forks – there is always something heavy to move e.g. engine blocks, transmissions, etc. and a pallet is an easy way to store/move it
3. auger – it is useful for fencing, but also planting fruit trees, or setting concrete piers

For storage of the skid steer and many other items (I’m using one for Hay), I have found the 40′ shipping containers very useful and economical compared to building the same volume. A 40′x8′x9′ container can be found for under $2000 in decent condition. The 20′ containers are only slightly less money for half the storage space. Just paint with rustoleum or killz oil based primer, and cover the roof with aluminum mobile home roof coating (to reflect back most of the heat).