Been lurking here for a few months, so I thought I'd better say something....
Noticed there's no mention of Westnet on here, so I thought I'd add them in.
Their website is
www.westnet.ie
I've had the wireless broadband since the end of March, and other than early teething problems all I can say is BRILLIANT!

When problems do occur they are sorted quickly by knowledgeable staff - and there's no bullsh*t.
Eircom are a no go for me (out in the sticks here), Irish Broadband told lies (said no problem connecting, then ignored me for 5 months - finally told me they had "capacity problems" - me arse they did! Their signal won't even reach half way here from their "high point"!).
I gave up on
IBB and stumbled across Westnet by accident one day - sent an email and about 5 days later I was up and running!
The installation is €199 and then €35 per month for a 1 meg connection. I very often get MUCH higher speeds than that (sometimes as high as 3 meg up and 4 meg down - pretty cool for what looks like an old colander stuck on the roof!). So far as I know they don't have any caps on how much you can download.
The areas they cover is a bit restricted, but if you are in one of them (falls under the Group Broadband Scheme) I'd recommend them without any reservations at all.
After being stuck with a flaky 56k dialup for so many years this really still does have the "wow!" factor for me - I still find it amazing that I can download a complete CD (650MB of Linux) in less than 50 minutes on a good day.
The only downsides that I can think of are the birds see the wireless aerial as a comfortable place to perch (.....not that great for the signal strength) and together with the sat dish and TV aerial the roof is looking a little crowded.