i have spend a great deal of time on the Betfair website the last couple of days and am amazed with the features offered. Compared to other bookmakers' websites, Betfair offers many a great feature in addition to what the others offer. Some features Betfair might consider (nice to haves):
a) sms and/or email notification of bet (placed) result
b) a LIVE BES link which lists a summary of live events, currently one has to follow a specific sport to get to the live bets; the summary on the home page is somewhat restricted
c) mobile: same as b) - this is particularly difficult on the mobile site as one has to follow many links to get to live events
d) download of profit/loss: total profit/loss, currently only available per sport. also total profit.loss across wallets
e) graphs for profit/loss
f) graphs for bets matched (monies, etc.)
g) notification via email/sms when an event is about to start (which i have put a bet on)
h) notification via email/sms when a Poker game is about to start (which i have registered for)
i) subscription offer (via email/sms) to notify one of new bets available for chosen categories
will add some more as i go through the Betfair website. Again, i really find the Betfair website in a league of its own!