What you need to decide first is what quality (and reliability) of maps you are after or, if indeed you want any map on it.
There is a whole load of American PDA software products, but their European map coverage is either missing, or full of omissions and (worse) errors. In this business, the product will be only as good as the number of users that regularly exercise the database, and with the GA scene in Europe being a bit on the small side, close to nonexistent in most places, and much of it being severely budget-limited, I am sure you can see that a product could easily get tested quite well between Goodwood and Bembridge, or even between Goodwood and Le Touquet, but once you get into the real winderness that's called "Europe" you can forget it. It will then be as good as the poor sod who compiled the database. And the database needs updating every 28 days, and somebody has got to do it, and there is no easy way to do this other than to obtain every country's AIP and see what has changed. It's a ludicrous [lack of] system which plays into the hands of the high end commercial vendors, Jeppesen and others, who have the manpower to run this, and charge for it very nicely.
There are plenty of W&B / E6B calculators and such. Just google on
W&B PDA
or whatever. Many are free.
IMHO, Navbox Pro is the best product to look at, by far. The price is good, it is fully updated and is as accurate as something costing 10x more, but there is no PDA version.