All journals windows—such as invoices for customers and vendors:
CTRL + R: Open recurring transactions
CTRL + P: Print or preview invoice
CTRL + A: Open the adjust invoice search window
CTRL + J: Open journal report
CTRL + K: Open the track shipments window
CTRL + L: Open the invoice lookup window
On your main page you can quickly open and search accounts using CRTL + F to open your chart of accounts.