Everlance - The #1-rated mileage and expense tracking app
Halfdollar - Free and elaborate spreadsheet budgeting.
QuickBooks Self-Employed - Track your self-employed income, mileage and tax owed.
Budgy 2 - Your best free budget assistant on the go
MileWiz - Automatic Mileage Tracking
Budgt - Track your ramen spending (iOS)