dazzam,
A 20 period exponential moving average is one of the more popular ones used on intraday time frames and is the basis for a number of entry methods.
If you are trading using an intraday time-frame, multiple moving averages are also often used to indicate the "trend" in a longer time frame (much as Skimbleshanks has shown on the longer term charts above).
So, many people who use a 20 period EMA on a 5 minute chart also incude a 60 period EMA on the same chart (which roughly equates to using a 20 period EMA on a 15 minute chart).
In this way you can get a view on where the trend is in the 15 minute timeframe whilst actually trading the 5 minute charts (maybe making sure you were always trading in that direction).
Whilst, I don't know of many traders using moving average cross-overs for trade entry these days, there are many that use moving averages in some other way.
With regard to timeframes, a common approach with a number of US traders (haven't come across it to much here) is to divide the trading session into equal slices, so instead of looking at, say, 60 minute charts, a lot of US traders use 65 minutes (since this divides exactly into the 390 minutes of the nyse/dow trading sessions. Personally, I've always found this approach more useful on the futures, but, nevertheless, a 65, 130 or 195 minute chart of the DOW does give a "slightly" different perspective.
To illustrate further, perhaps you could try an 85 minute chart on the ftse?
Anyway, just some ideas. Good luck.