u-Bob

First of all, be sure to talk to your accountant. Things can get complicated and there are different ways to structure things and the solution you choose will depend on how much you're planning/hope to make.

Technically, as a non-EU company selling services that take place inside the EU, you will have to charge VAT. Most EU countries have different VAT rates (from +- 15% to 25%).

You could charge VAT based on the country of the buyer (and then deal with the VAT administrations of each country)
or
you could register in 1 country (one with a low VAT rate) and then only deal with the VAT administration of that country. In that case you'd charge VAT to clients from that country (both VAT registered and unregistered clients). If the client is based in another EU country and is VAT registered (in other words, if he has a valid EU VAT number), you do not charge him VAT. If the client is based in another EU country and is not VAT registered, you do charge him VAT (you charge the VAT rate for the country you are registered in. Not the VAT rate of the country the client is based in). Clients outside the EU won't have to pay VAT.

In situations where you don't charge VAT because the client is VAT registered in another country, be sure to check if the VAT number that he supplied is valid. There's scripts out there you can use to run the number through VIES (EU site to check the validity of EU VAT numbers). Note that in a few EU countries a local VAT number is not automatically a valid EU VAT number. In most countries however, a local VAT number is also automatically registered as an EU VAT number.

Also note that every country has it sown special rules about what to put on your invoices. So if you register in a certain country, it's possible that you'll have to put a specific reference to a local law/regulation or to for example EU Directive 2006/112/EG or 2008/8/EC on your invoice if you do not charge VAT.

my advice: try to get an idea of how much you will be making and talk to your accountant.