also, my answer is relevant because with more users comes expansion. my social networking site (before the phrase was coined so feverishly) started with 10 people initially signing up. i had launched the day prior to my vacation and didn't return for 2 weeks. word-of-mouth spread it like wildfire and when I returned... 20k people has signed up. with that however, came the server and bandwidth bill (I was using a shared hosting plan). technically, it made me broke for time (fixing everything that broke and eventually broke during my transfer to the dedicated server) and financially it drained me (back when dedicated servers cost and arm, leg, first born and your dog fluffy). =P
I'd like to create a technical solution for those non-technical problems just so I wouldn't hate so much to deal with them.