Focus on your audience, not on yourself.
Focus on the one thing -- not three things, and certainly not fifteen -- that makes your company distinctive from your competition.
Think about your brand personality: cute and perky? bold and strong? serious and thoughtful? Now look for vocabulary and constructions that fit your personality.
Use Twitter to practice distilling your message. Nothing like a 140-character limit to force you to be succinct.
Use the thesaurus tool at Visual Thesaurus to explore constellations of synonyms: www.visualthesaurus.com In your case, I'd focus on words from the lexicon of music.
See my posts on building a better tagline: http://nancyfriedman.typepad.com/away_with_words/2012/03/building-a-better-tagline-part-2.html
There's still a music industry?
Sorry, couldn't resist that initial snarky answer. I was a guitarist, vocalist, songwriter and producer in the '80s in San Francisco, and every year since I got out, the "industry" has been shrinking - at least for everything below the level of top-flight, international labels. I agree with the other respondents, your first focus should be on defining exactly who your audience and customer base is.
And there's the rub for the "music industry" - finding a group of people who will spend money to enjoy, make, learn, or collect music these days. Now that every phone is a tape recorder and video camera, and every laptop is a 48-track recording studio, and the price of picking up or creating new music has essentially dropped to zero, the hard part is finding a market where money is actually exchanged for something - anything! - in the music world.
If you have figured out a way for somebody to make money related to music - make sure you put THAT part in your pitch, because that is the equivalent of a unicorn in today's economy, and will attract investor attention.
As far as resources, many people in the naming business also work to develop taglines and other promotional writing - sometimes called "verbal branding". Take a few calls with people who specialize in "branding" on Clarity here, and you will find people who are used to developing the super-concise, action-packed lines used for taglines and pitches.
Another type of professional you might talk to are people who write screenplays, because they are not only experienced at writing compact, evocative language, but they must also constantly create "loglines" for their work, where they are essentially tasked with shoe-horning the entire impact and feel of a 2-hour movie idea into a single sentence, for promotional purposes. That's perfect training for creating great pitches and taglines.
Good answers aplenty already from my colleagues.
1 thing I'd emphasize is this: You won't FIND a ready-made solution using existing resources. No, you must INVENT your brand and test it on people.
If you can watch them being persuaded while you say the tagline or give the pitch, then it works. Browsing online won't tell you that. Talking to people will.
Suppose you were writing a story. You wouldn't ask for the "best resources to find the perfect opening sentence". That's crazy! Such things aren't out there to be found. They're made.
So my advice is ... If you're stuck, hire a pro. Once you have a pitch and a tag line, try them out and see if they feel effective.
There are tons of resources and templates online to help you develop an elevator pitch. I will keep this short and just say that the one thing you need to do is be flexible. Just because you come up with one, doesn't mean you have to keep it forever. Hell, change it every month and see what resonates the best for your audience. Get feedback and keep tweaking until you get something that works.
This might help: http://pitchdeckcoach.com/pitch-deck.
Think of your tagline as the tip of your pyramid. Your elevator pitch is the next level down. And you pitch deck is the base of the pyramid. Your elevator pitch should be a 30 second summary of your pitch deck and your tagline should be a 10 second summary of your elevator pitch.
In the example I link to above the tagline would be something like: "On demand mobile auto detail for busy office workers"
For investors, you can sometimes use a comparative tagline.
Investor version: Lending Tree for real estate agents
Consumer version: Let real estate agents compete to sell your home.
I think your question is not specific enough, which is why the answers go in 10 different directions. All of them have good things in them though, depending if that was what you were really asking for.
Here´s some things you need to clarify (for yourself, really):
1) What type of pitch are looking for, i.e. what format (1-Sentence, 1-Minute, 5-Minute, ...), but more importantly: what´s the TARGET AUDIENCE for the pitch? Do you want to pitch potential customers, investors, partners, ...? Only if you´re pitching customers will the pitch be anything resembling the tag line (which is always targeting customers). If you´re pitching investors, that pitch has nothing to do with the tag line.
2) What´s the GOAL of your pitch? (this is one founders always forget!) Your pitch is never just "your pitch", it has to change a lot depending on what you want to achieve and who your audience is.
Other than that I agree with the statement in one of the answers: the resources are a starting point at best, you really need to check with the target audience if they get the pitch and if the pitch gets them emotionally. There´s 100 "formulas" out there, but the challenge is to find the formula that´s right for your business. People always tell founders to find a comparison to an existing startup, which can be great if it works, but it rarely works. Seen too many "Uber for Spaghetti"s to still recommend that to anyone. ;-)