(No, I'm not trying to 're-envision' how techs work in 0ad, don't worry!) 
A while ago, Pureon showcased some of the icons the art team had been working on (http://www.wildfiregames.com/forum/index.php?showtopic=17025) and along with a selection of icons, he also displayed a Tech/Structure tree concept: 
  
  
I liked the idea (as did the commenters in that topic) and so I decided to attempt to implement it - with a little interpretation. After months of on/off development (mostly off than on) and various revisions, I have got it to a point where I'm happy to share it with the community. 
Here's a screenshot:  
  
A live interactable version can be found here: http://s06eye.co.uk/0ad/techtree-v2 
And the code is on github here: https://github.com/s0600204/0ad-techtree-v2 
Please note that this is no more finished than 0ad is. There are changes to come, efficiency improvements, appearance tweaks and such. But I thought I'd share my progress and get some (hopefully favourable) feedback. 
Enjoy! 
Update! It is now possible to see this in-game. See this post for details! 
Code Updates: 
21st October : Tooltip positioning is better. 
22nd October : Stats are now loaded from parent templates properly 
23rd October : Tooltips now have the same descriptions used in-game; and for units and structures, attack and armour stats are shown where applicable. 
3rd December : Three more community mods available for comparison, rewrite much of the data parsing code. 
30th March : Big update to mods' simulation data, and modifications to permit aristeia's phase-pair techs