The Alliance Alive's secondary "growth" system, which gives you things like reduced SP costs, works like this.

The Dark Spire (DRPG for the Nintendo DS, feels a lot more like Wizardry 4/5 than most Japanese DRPGs) did something similar; you get XP from enemies, and you can spend it to gain levels (there's even the option of multi-classing, which leads to advanced classes later) or use it to gain skills (many of which are useless, and some which only see use in an event in the post-game floor). Oh, and attribute points are also purchasable with XP. Was rather interesting. (Also, spellcasting resembles 5th Edition D&D, yet this game came out first.)

There are games that do it fully, but they're rare. Like Evil Islands (where the early pain for later gain thing is in full force, since all costs increase whenever you improve something, so must always wait until you can take the most expensive you think you may want first) or (if I remember correctly) Vampire: The Masquerade: Redemption (can also say Bloodlines, but the way that works is rather different, what's called exp essentially being skill points granted for completing quests).