One idea: If you came up with a model to calculate a "fair price range" for a stock, then any time the market price were to go below the range it could be a buy signal, and above the range it could be a sell signal. There are many ways to do stock valuation using fundamental analysis tools and ratios: dividend discount model, PEG, etc. See Wikipedia - Stock valuation.
And while many of the inputs to such a "fair price range" calculation might only change once per quarter, market prices and peer/sector statistics move more frequently or at different times and could generate signals to buy/sell the stock even if its own inputs to the calculation remain static over the period. For multinationals that have a lot of assets and income denominated in other currencies, foreign exchange rates provide another set of interesting inputs.
I also think it's important to recognize that with fundamental analysis, there will be extended periods when there are no buy signals for a stock, because the stocks of many popular, profitable companies never go "on sale", except perhaps during a panic. Moreover, during a bull market and especially during a bubble, there may be very few stocks worth buying.
Fundamental analysis is designed to prevent one from overpaying for a stock, so even if there is interesting volume and price movement for the stock, there should still be no signal if that action happens well beyond the stock's fair price. (Otherwise, it isn't fundamental analysis — it's technical analysis.)
Whereas technical analysis can, by definition, generate far more signals because it largely ignores the fundamentals, which can make even an overvalued stock's movement interesting enough to generate signals.