If you are looking at sending something traditional, such as a bunch of red roses, a good place to start is Roses Only at rosesonly.com.au They are allowing customers to make online purchases today and have them delivered before the end of the day.
As you may have already noticed, most sites will not deliver goods with 0 days' notice. Perhaps an e-voucher is the way to go. It is immediate and no delivery of a good is required. It may not be the most romantic thing to do, but if you can talk you will probably save yourself. Try looking at evoucher.com.au for perhaps a balloon flight from Global Ballooning or giftvouchers.com for maybe a wallet from leathergoods retailer Oroton.
Of course, this being the last minute and all, you may want to go to lastminute.com.au. Perhaps organising something for the weekend may be a lot simpler, as all deliveries of Valentines consumables will not be received by your lover today; unfortunately, most courier companies need advance notice. This looking forward to the weekend may also cover you for your lack of foresight earlier in the week.
If your lover does not fuss about the immediate and you are one that is more inclined to buy online than in the flesh, you may find these local sites helpful in the future. Wishlist.com.au, dstore.com.au, perfectgifts.com.au all offer general gift ideas. For that something more sensuous, efragrance.com.au may be the way to go.
Finally, if you have decided against spending lots of money then your cheapest bet is an e-greeting. You will find lots to choose from www.freewebcards.com and www.123greetings.com. For a musical greeting try www.clubgreetings.com and for a video greet go to www.hotgreetings.com.