Do a “fast reply” to this thread and put your links. Once we get a few, I will perhaps create a wiki article with links.
(note: non commercial or informational-based articles please)

Four Way Mix Valves
Tarm Boiler Wiki Article

Here is a quickie calculator to figure out what water storage may do for you!
http://www.hearth.com/econtent/index.php/articles/using_storage_tanks_with_biomass

Nofossil site: Wood Boiler / Heat Storage / Solar Hot Water

DIY Gasifier Links:

http://www.hearth.com/econtent/index.php/forums/viewthread/11492/

A collection of gasification articles about gasification and one about hydronic heat. Great stuff!

http://www.hearth.com/econtent/index.php/forums/viewthread/13659/

How to calculate the size of an expansion tank for pressurized hot water storage (Page 2).

http://www.hearth.com/econtent/index.php/forums/viewthread/11559/P15/

http://www.stiltman.com/html/doe_report_part_ii.html

Very interesting and informative report on bio-mass burning, and potential. It was prepared for the US DOE
leaddog

found this on youtube, amazing burn rate.

http://youtube.com/watch?v=DNYCfgEdYpg

Piping diagrams and more piping diagrams. The Atmos site contains seemingly every piping configuration imaginable for a gasification boiler.

http://www.atmos.cz/english/instalace-kotlu-006-dalsi-doporuce-zapojeni

Here’s another one - the title makes you think it focuses on pumps, but it actually seems to cover a lot on heating systems, too

http://www.wilo.co.uk/cps/rde/xbcr/gb-en/basic-of-pumps.pdf

(from Wilo, apparently the largest maker of pumps, and maker of nothing but pumps, on the globe)

I thought this was a good one…........... I guess this link is on aqua-stats but this site has tons of other stuff….............  http://www.inspect-ny.com/heat/aquastats.htm

several interesting articles on this page from Plumbing and Mechanical magazine’s site at http://www.pmmag.com/Articles/Radiant_Heating_Report

The site and magazine are a great resource.

in case you were wondering about under-slab insulation….http://www.pmmag.com/Articles/Column/BNP_GUID_9-5-2006_A_10000000000000372298

wonder no more!

as boiler efficiencies are approaching practical limitations, John Siegenthaler makes the argument that consideration of system electricity consumption is the next frontier in reducing over all system operating efficiency and cost.  see his thoughts at http://www.pmmag.com/Articles/Column/BNP_GUID_9-5-2006_A_10000000000000479795

Ten Trends in North American Hydronics - John Siegenthaler

http://www.pmmag.com/Articles/Column/BNP_GUID_9-5-2006_A_10000000000000149223

Nice post here. It give us a lot of information.

wndair
Dossier de surendettement

http://blog.woodboilers.com/2009/06/properly-sizing-pex-pipe-for-remote.html

Very nice and practical article for selecting pipe/pump combinations that will work. They are doing their customers a good service. It will make it easy for new installers to select from a table a combination that has allready passed the formulas and keep fluid dynamics for another day. Possibly never ...

http://flatplateselect.com/site/pub/login.aspx?ReturnUrl=/site/Default.aspx

here is another that I cant say enough about. Understanding the impact of liquid material, flow rates, BTU loads, temperature differentials would have you pulling out hair. Use this tool to find and size the HX and flow rates you will need to get the heat out of your boiler and into your tank. Make doing what if I ... variations simple. I wish I had bought my HX from them to say thanks. ( You have to sign-up/login , it’s free and what is on the other side is well worth the trouble )

http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

This has disclaimers about accuracy but it was dead on for my home and allows a DIYer to cut the crap and get a working number for the BTU load. I cross checked the results by comparing the annual estimates with the Gal of propane I actually purchased. Scary close almost like it is not magic just basic science. I have a year now of watching tank loss and outside temps to say the number this site allowed me to get ( Without fancy software or Hiring a manual J calculation ) was right on.

For a person looking to get started these 3 are gold. They answer some of the big starter questions, how much heat do I need, What size: boiler/tank/pipes/pumps/HX and then you can start to get an accurate cost in mind.