Try not to be everything to everyone.
This is where things become ambiguous when you get all things done at the same time. If you can, be specific about what you do and what you can still do.
Google maintained its reputation as the "only" search engine in the universe - with a few added valued services such as Adsense, Gmail, Bookmarks, etc. But it's essentially a search engine. If Yahoo was launched at this time, it wouldn't have made it. It started as a portal and it finally decided to stay as a portal. So it survived.
Microsoft on the other hand thought they wanted to be like Google with a new service called Bing - they say it stands for "But It's Not Google". This is going to be interesting.
In the local music circuit, Alex Lim of Sonic Boom Philippines realized this difficulty and later decided to focus on events instead - with added valued services on merchandising. My previous website Indie Culture Online failed because it wanted to become the "best indie website in the world" when what it actually was was just a small scale music e-zine.
I ended up chewing more than I could swallow.
Case in point... we only got two hands and a brain. Don't overuse it.