I wasn't aware the 2 character restriction applied to .COMs ... I know it does to .ORG though.
In answer to your question, I'm not aware of any ... there are only 676 LL.com combinations - not very many compared to LLL (17,576), which are all taken, and even LLLL (456,976), which the large bulk of them, amazingly, are taken too.
On an aside, shorter does not automatically mean more valuable for various reasons (one of which is extremely short acronyms can be difficult to brand / protect; lack meaning) - many of the highest sales I've seen sold throughout the industry have been domains somewhat more than 2 characters long...
Still many nice 4 and 5 letter domains out on the drops / forums at reasonable prices.
Ron