I use Wealthfront, which allows you to park your money into an account, and depending on your level of risk, will automatically balance it across the US Stock Market, dividend stocks, emerging and foreign markets, bonds, and natural resources.
For account values over $100K, they will do tax loss harvesting for you automatically, and prevent wash sales. For over $500K account values, they will actually buy stocks for the entire S&P 500, and allow you to take tax losses on individual stocks (which you can't claim on ETFs).
An important note on tax loss harvesting: it only defers taxes. If you'll be in a lower tax bracket in the future, that can be good; but if you'll be in a higher tax bracket when you need the money (eg house down payment), tax loss harvesting will actually cost you money, so beware.
This can be balanced against the fact that you get to invest and compound that deferred tax until you do end up paying it, possibly several years later. So instead of multiplying your account by .65 every year (assuming 35% tax rate), you only multiply it once, at the end.
For account values over $100K, they will do tax loss harvesting for you automatically, and prevent wash sales. For over $500K account values, they will actually buy stocks for the entire S&P 500, and allow you to take tax losses on individual stocks (which you can't claim on ETFs).
I found their presentation to be quite helpful:
http://www.slideshare.net/adamnash/personal-finance-for-engi...
If you want an invite, PM me.