Trying to avoid a "commercial" type post, but since this is taxpayer funded and I don't get anything out of it...
I work at the National Oceanography Centre and we've been working on our first iOS app for tide prediction. It's called anyTide and it should be released in the next couple of weeks.
Like other tide apps, you can get predictions from 44 known ports around the British Isles. However, anyTide also lets you zoom in on the map to any coastal point and get a tidal prediction for that point (actually to the nearest 1.8km grid). It does this by using some very clever tidal models developed over many, many years at NOC Liverpool (and its predecessor the Proudman Oceanographic Lab). So, if you want the tide at St. Catherine's point (or Portree or Kilkeel...), it's possible.
You can't get tide tables out of it (but you can use a cursor to see the tide height at any time on the curve.
All tide data will be free up to the end of June 2013. After that, only 1 or 2 days will be free (can't remember which). An in-app purchase gives you a calendar year of tide data anywhere for £1.49. You can bookmark locations and you don't need to be online to get tide predictions for previously bookmarked points.
It's our first app, so if anyone does use it, I'd be really interested in feedback.