Great news! You can now use Zapier (rhymes with "happier") to connect Wave with potentially hundreds of different applications, and automate your workflows. (See the guest blog post from Zapier's Alison Groves.)
Say you create a new invoice in Wave for a brand new customer. Now you need to get that customer into your CRM; add them to your email marketing list; send an email to that customer to thank them; maybe even create a follow-up task in your to-do app.