Cub

Well if it helps I will tell our story. We met online on a dating site. I actually can't remember informing USCIS of exactly when that was. I visited him for 10 days in April, 3 weeks in May, visited again in June and married 2.5 weeks into that visit, in July.
So I don't think it is an uncommon situation.

My husband & I married when he was here on a vacation about 80 days into his VWP we had no intention to get married but I convinced him & we have now been happily married over 4 years, we adjusted status from VWP & had no problems at all but we had known each other a while & it was very obvious we had a real marriage. VJ has been there all the way for us it is really good. If you have a real marriage & entered with no intention to marry you will be fine.

Don't get caught up in the paranoia, you should be fine to AOS. Make sure you have as much proof as possible of a bonafide relationship, joint bank accounts, insurance, credit cards, wedding pictures and cards from family members, etc. If you have saved e-mails from your relationship prior to marriage, that works too. Also phone call records will be helpful. Make sure to take pics and document everything you can from now til your interview.
Good Luck!

Allen,
You really have two issues here: the IRS issue and the immigration issue. As to the IRS issue, if you were on unemployment in 2010 and 2011 I would assume that you are not liable for any additional income taxes. You're only required to file a return if you owe taxes or you want to collect a refund of overpaid taxes. You didn't mention your 2012 return, but assuming that you got an extension your 2012 return will be due on or before October 15, 2013, and your 2012 return should be the tax return that you include with the I-864. So go ahead and get your tax returns filed. Make sure you keep copies of all of your returns, W-2s, and 1099s, because with the government shutdown affecting the IRS as well it may be many weeks before you could obtain a copy of a tax transcript.
As far as the immigration issue goes, USCIS is only looking at your financial status, and is using the tax information to determine your income. USCIS doesn't care and has no jurisdiction over whether you filed your tax returns late, it just wants to see the financial information. If you have a tax due balance with the IRS that is large enough, the IRS could file a Notice of Federal Tax Lien against you, but at most USCIS would deduct the amount on the lien from your annual income for purposes of calculating your financial position.
The bottom line is that you will probably still need a joint sponsor, but based on the information you've given the additional work that you'll need to do to get current on your tax returns should not cause you problems with the IRS (assuming that you do not owe any additional income tax) or USCIS.