After recommendations on this board I went ahead with Interactive Brokers (
http://www.interactivebrokers.com). I have to say I have been impressed. I am using it for a long term buy and hold strategy, with regular purchases (bi-weekly/monthly).
The bad news: €10 per month account maintenance
The good news: $1 per transaction typical for US share purchase, €4 for funds/etf/European shares. (up to approx $/€50k)
I believe that the account maintenance is reduced by your transaction amount, so if you make €8 worth of transactions in a month, your maintenance fee in that month will be €2.
As far as I can see, you can trade pretty much anything. I am currently holding US equities in dollars, German ETFs in Euro, Oil/Gas through UK ETCs and European stocks directly. See: [broken link removed] under "Trading->Product Listings"
I am using AIB's free IBAN transfer to fund the account and it is working great. The reporting is excellent, so tax returns should be ok.
I was very worried when I saw the Trader Workstation platform as it is very much geared for the professional day trader, but you can use the WebTrader platform for pretty much everything and it works great (there is a new version just out).
The only gotcha that I was not aware of was that you have to subscribe to real-time quotes for the different markets. All US real-time level 1 data is free if you spend more than $30 per month, or $10 per month otherwise. One German exchange is €1 per month for real-time quotes. You could get your quotes from somewhere else of course.
On the security of the company: Read
http://www.interactivebrokers.com/en/general/about/ibgStrength.php?ib_entity=llc
All in all I am very happy - it has taken me a bit of time to get used to; but the cost of trading, range of products/markets are amazing and definitely something that you can grow into.