What alerts or notifications do you think would be useful? Most common i would think of are Price change threshlods, price change percentages.
And do you know of any websites that provide such?
Download an app on your phone called "Bitcoin Ticker Widget." One of the best mobile apps to monitor.
As for monitoring price changes, your charts should be from Trading View, Coinigy, or
https://cryptowat.ch/ Which all have built in "alarms" for price thresholds.
Here's an example from Bitfinex that uses Trading View. See that "Alert"?