The Tongues spell does exactly what you'd like and its on your spell list as a bard.
If you really want it in a magic item, there are three avenues.
The first is a bit of a cheat (since it just devolves into spending skill points). Get a headband with intelligence in it. This will grant you a number of ranks in a skill equal to your level. Put those in linguistics and you're golden.
The second way I know of is to create a custom magic item using the item creation rules (if your GM allows it). It would be based on the Tongues spell. As a continuous effect, it would be priced as 2000 x spell level x caster level. Since Tongues lasts 10 minutes per level, you would also need to multiply by 1.5. So, the cost would be 2000 x 2 x 4 x 1.5 = 24,000 gp for a slotted item. Twice the cost (48,000 gp) for slotless. Very expensive, but allows you to speak and understand any language any time you like.
Lastly, a Helm of Telepathy might work. It would probably allow you to use Suggestion, but probably not performance (depending on what kind of performance it is). Not perfect, but gets you some of what you're looking for.