Unlimited Data Plan Europe [closed]

You can get a T-mobiles simple choice plan (in the US) with unlimited international text and data. It works in almost every European country. Technically it's only 2G guaranteed but it tends to work well in most urban areas since there is no 2G anymore and you get upgraded for free to 3G. Total cost will be around $300 or so: you need to sign up, get the cheapest simple choice plan for two months and get a phone. You may be able to bring your own phone, if it's T-mobile compatible which would knock this down to below $200. If you already in T-mobile or want to stay with them and ditch your current carrier, this is all basically free.

Stating the obvious: By far the best choice in getting lots of data internationally is WIFI. Not sure where you are going but there are plenty of opportunities for cheap or free Wifi (hotel, cafe, restaurants, airports). I recently sat in a park in Amsterdam and had 50+ WIFI networks in range (not all of them being locked :-)).

If you need data for navigation, you can use apps like HERE maps where you can download an entire country (while on WIFI) and then simply use it off-line.

500mb is quite a bit. Have you considered using wifi when available? In my experience there's quite a bit of wifi just about everywhere and I rarely have to use my roaming plan on trips abroad.

To answer your question, I don't know of any decent-priced plans that offer 500mb per day in other countries than the home country. I can point you to the plan I use though, which I'm satisfied with. It is one of the better deals available for roaming in the Netherlands.

Vodafone Netherlands offers pay-as-you-go 'contracts' called BloX. Two of these are aimed at roaming. There's a small bundle and a bigger bundle. They are daily 'contracts' to use abroad. Nearly all European countries are included. And if you cross a border that day, you don't have to pay twice. For 2 euro per day you have 35mb internet and for 4 euro per day you have 100mb.

Sadly, the website is only available in Dutch, but that may not be a problem for you, judging from your location. Anyway, here's a link to the pay-as-you-go sim cards.

T-mobile in USA has a normal-priced plan that includes unlimited data in all european countries (and most of the rest of the world).

It gets slowed down after certain (country specific) amounts, but you did not state speed requirements; also, they offer (by sms) to speed it up again for additional payments (with country specific cost)