"Don't make me think"
A quick "driveby" on your promoted domain name "thisizsparta.com" has little meaning to me, and i'm not quite sure what it would be about, nor would I know it would be about startups.
(and yes, I saw "300" , but again, given urban use of the phrase, "this is sparta" could mean almost anything)
If you want to promote the sparta connection, the front page needs a quick and dirty what it means to the target audience & why it describes them (oh, and promote activity). Even Fmylife.com has a faq entry that describes what they are all about.
I would also change the logo on the top "this is startup" since it would confuse those who thought "hey, isn't it supposed to be 'this is sparta' ?).
thisisstartup.com seems a lot more on message - and would probably resonate better with your target audience. Tell visitors from "thisizsparta" that going forward the site will be called "this is startup" (a top announcement strip would do fine).
FMLife is pretty straightforward - "Today, this happened. FML." Mimics real world conversations. People add it to the their story, since it is almost natural. FML just happens to be related to the domain - you don't see many posts ending with "fmylife".
I don't think you will be able to enforce people to end with "thisizsparta" or "thisisstartup" since it doesn't not mimic real world conversations - and would look forced.
If you had the name "just another day in startups" One could finish the story "Today, this happened. JADIS."