For a tiny investment of £19 (approx $25, approx Euro 22), you can optimise your (bootstrapped) osCommerce shop in the following ways;
1. All new Social Icon system
Proven system that replaces the stock Social Icons. Speeds up your site.
2. Popup Boxes
Two versions of Popup boxes (uses Bootstrap Modal).
Exit box (ask why people are bailing out of your site? give them an offer to complete checkout?)
Pageload box (popup after X many pageloads).
3. Formatting UK postcodes
Hook in create_account and a shipping module for postcode delivery
4. Googles Address Autocomplete
Use googles technology to allow address finding in create_account.php
5. Facebook Dynamic Ads
Utilise the power of Facebook for promotion.
6. A bunch more modules
Navbar, Content, Header Tags
Read more here.