I see a lot of posts with people using the faction availability of the canon Master Unit List for their games.
I wanted to highly recommend AGAINST it, well, unless you are playing in the Jihad era. The data simply isn't there.
As of the 19th of June, the last time I got all the canon MUL stuff, there were 5519 units within it (10% of which aren't even published yet, which is kind of annoying to many I bet).
The Age of War, Star League, and Early Succession Wars have data for only THREE of those units, and all 3 are "unavailable". The rest units are simply blank with no data. Late Succession Wars has 4 with data, Clan Invasion 6, Civil War 5, and Dark Age 2. None of these eras can you use the current MUL for.
The Republic era has data for 5421 units, HOWEVER, 4858 of those are "To be announced", leaving 563 with a faction, the rest are blank, so about 10% complete. So, you can't use this era either.
The ONLY era that is anything close to complete is the Jihad era, which is about 90% complete with 5001/5519 units having data. You can use this era, but know that about 10% of the units will simply never show up in any searches for a faction's available units.
One of my pet peeves on the whole MUL is the amount of errata I gave them that has *still* yet to be fixed. Actually, I'm pretty sure for a while before I was banned I was the lead poster to issues with it. My MUL/QS creator thing still works tho, not sure if people are still using it. Heck, how many of ya'll know I wrote an application to create detailed infantry platoons a while back? :)
I have also seen a lot of complaints of issues on the availability and eras, but this is an insanely difficult task so its understandable.
It would be pretty easy to write up a site or application that would help with this massive undertaking. For example, you log on, ask for the next unit. It then assigns you a unit based on the source material you configured that you had. You then go through, verify the year, known eras, etc. When done you check complete and a checked flag gets set to "Checked +1". Each time somebody checks an entry checked goes up by 1 so you can see how many times a unit has been checked, and by who. The lower the number, the more likely you are to see that unit when you request a new one.
I'd offer to do it and invest the time to keep it updated daily, but the battletech folks don't like me very much and would probably rather eat a miniature than deal with me ever again :)
On other news, MechWarrior Online allows you to give them money now. I blew $120 on a legendary pack for Bad_Syntax (I have 7 other names, some of which are BT canon that I didn't upgrade). Sure hope the game is as great as the movies are making it seem it'll be. We'll see soon, August 7th I get to do the beta! It'd be cool if they'd open their API a bit for a spectator mode. It'd be cool to see an overhead map, then you could draw megamek icons moving around as they are in MWO. Well, cool to me :)