uConvert

Features:
19 unit types/categories
Convert between more than 25 different currencies
Latest exchange rates are downloaded automatically when you start the app
High resolution VGA and WVGA graphics (QVGA and WQVGA available)
Slot machine style interface lets you select your conversion quickly
Add favorite conversions and sync them online so they'll never be lost
Switch a conversion quickly – with one swipe swap from $500 in €s to €500 in $s